Patent Application
20240429818
The efficiency of radio-frequency (rf) power amplifiers (PAs) can be improved through “supply modulation” (or “drain modulation” or “collector modulation”), in which the power supply voltage provided to the PA is adjusted dynamically (“modulated”) over time depending upon the rf signal being synthesized. For the largest efficiency improvements, supply voltage can be adjusted discretely (among discrete levels) or continuously on a short time scale that tracks or dynamically accommodates rapid variations in rf signal amplitude (or envelope), such as may occur as data is encoded in the rf signal or as the rf signal amplitude is desired to be changed with high envelope bandwidth (e.g., as in envelope tracking, envelope tracking advanced, polar modulation, “class G” power amplification, multilevel backoff, multilevel LINC, Asymmetric Multilevel Outphasing, etc.). The power supply voltage (or voltage levels) provided to the PA may also be adapted to accommodate longer-term changes in desired rf envelope (e.g., “adaptive bias”) such as associated with adapting transmitter output strength to minimize errors in data transfer, for rf “traffic” variations, etc.
“Continuous” supply modulation (e.g., “envelope tracking” or “adaptive bias”) may be advantageously realized by dynamically selecting an intermediate voltage from among a set of discrete power supply voltages and then further regulating (stepping down) this intermediate voltage to create a continuously-variable supply voltage to be provided to the PA, or by pulse-width modulating between two or more levels and filtering the output to create a continuously-varying waveform.
Some rf amplifier systems utilize “discrete” supply modulation (or discrete “drain modulation”) in which the supply voltage is switched among a set of discrete voltage levels, possibly including additional filtering or modulation to shape the voltage transitions among levels. Systems of this type include “class G” amplifiers, multilevel LINC (MLINC) Power Amplifiers, Asymmetric Multilevel Outphasing (AMO) Power Amplifiers, Multilevel Backoff amplifiers (including “Asymmetric Multilevel Backoff” amplifiers) and digitized polar transmitters among other types. Hybrid systems which utilize a combination of continuous and discrete supply modulation may also be realized.
Described are concepts, systems, circuits, devices and techniques for use in and/or with PA architectures using supply modulation. The described concepts, systems, circuits, devices and techniques can provide both very rapid variations in modulated power supply voltage (e.g., among multiple discrete levels) while also providing the ability to slowly adapt the voltages of the discrete levels over a desired range. Such concepts, systems, circuits, devices and techniques find use in a number of applications including, but not limited to PA architectures.
Using descried concepts, systems, circuits, devices and techniques, it is possible to efficiently and compactly generate a set of m power supply voltages. Two of the m power supply voltages (e.g., V1 and Vm) can be independently controlled. The other m−2 power supply voltages can be distributed in some prescribed relation to the two independently controlled power supply voltages, such as spaced in an even fashion between them and/or around them (e.g., with adjacent voltage levels each separated by an approximate voltage ΔV). Thus, for example, the following m power supply voltages can be provided wherein V1 and Vm are the independently controlled supply voltages:
Such an arrangement is equivalent to allowing for independently specifying or controlling:
The concepts, systems, circuits, devices and techniques described herein provide substantially all (or most) of the practical benefits available from supply modulation (e.g., in terms of PA efficiency) while at the same time avoiding limitations associated with providing truly independent voltage level control or ratiometric levels. Thus, the concepts, systems, circuits, devices and techniques described herein provide significant advantages in combinations of size, cost, efficiency and performance as compared to existing approaches.
Further benefits are provided if one only need generate two regulated supply voltages and be able to directly provide one or more additional supply voltage levels to the PA, without the necessity of having a separate supply generator element to generate these additional levels cascaded with a supply modulator to select among the levels. Merging the functions of intermediate level generation and supply modulation can reduce the number and size of passive components (e.g., capacitors) required as well as the number, required area and loss of semiconductor elements (e.g., switches).
In accordance with one aspect of the concepts described herein, a system includes: a differential multilevel converter comprising: a differential input including a first input terminal configured to be coupled to a first voltage VA and a second input terminal configured to be coupled to a second, different voltage VB; a plurality of switches SA, SA′, SB, SB′ coupled between the first and second input terminals; and a capacitor Cf having a first terminal coupled to a first terminal of a first one of the plurality of switches and a second terminal coupled to a first terminal of a second, different one of the plurality of switches; an output terminal coupled to a first terminal of a third, different one of the plurality of switches and a controller coupled to the plurality of switches and configured to control selected ones of the plurality of switches SA, SA′, SB, SB′ to switch, at points in time, between a plurality of switch states with each switch state producing an output voltage Vsm corresponding to one of three discrete voltage levels L1, L2, L3 at the output terminal of the differential multilevel converter and wherein: at least two of the plurality of switch states produce an output voltage which is substantially the same and at those points in time when ones of the plurality of switches switch among the at least two switch states producing the substantially same output voltage, the controller seeks to maintain a voltage Vcf across the capacitor Cf within a voltage deviation ΔV of a target voltage and wherein the voltage deviation ΔV determines a maximum deviation of the substantially same output voltage from an ideal output voltage.
With this arrangement, a system may synthesize one of three discrete voltage levels from a differential input. That is, from two supply voltages, the system operates to to directly provide one or more additional discrete voltage levels. Such discrete voltage levels may find use, for example, in a discrete digital envelope tracking system in which such discrete voltage levels may be provided to a supply terminal of a power amplifier (PA) in a base station (e.g., a base station of a cellular system) or mobile hand set (e.g., a cell phone or other mobile device), without the necessity of having a separate supply generator element to generate these additional levels cascaded with a supply modulator to select among the levels. Merging the functions of intermediate level generation and supply modulation can reduce the number and size of passive components (e.g., capacitors) required as well as the number, required area and loss of semiconductor elements (e.g., switches).
It should be appreciated that individual elements of different embodiments described herein may be combined to form other embodiments not specifically set forth above. Various elements, which are described in the context of a single embodiment, may also be provided separately or in any suitable or reasonable sub-combination. It should also be appreciated that other embodiments not specifically described herein are also within the scope of the following claims.
Accordingly, system, circuits and techniques described herein may include one or more of the following features independently or in combination with one or more other features to include: a differential multilevel converter comprises switched capacitors configured to synthesize instantaneous voltage levels while enabling desired voltage/charge-balance on the capacitors; a differential multilevel converter comprising a differentially-connected flying-capacitor multilevel converter (FCML); a differential multilevel converter comprising a capacitor-based energy-transfer topology in which the charge transfer requirements prevent one or more of the synthesizable levels to be continuously provided without switching of the differentially-connected multi-level converter; a first switch SOpt,A; and a second switch Sopt,B with the first and second switches configured to enable direct energy transfer from output A (e.g., VA) to output B (e.g., VB) or vice versa; a multi-output regulation stage provided as one of: (a) a magnetic regulation stage; or (b) a hybrid magnetic/switched-capacitor regulation stage; a multi-output regulation stage of claim comprising a pair of output decoupling capacitors; and a differential output decoupling capacitor; a differential multi-level converter configured to receive at least a first voltage VA and a second voltage VB, and combine a differential capacitive energy transfer supply generation function with a supply modulation function to thereby provide the differential multi-level converter having an area and size which is reduced compared to an area and size required to provide like first and second voltages VA, VB using a differential supply generator which is separate from, but coupled to, a supply modulator; a differential multi-level converter in which the second voltage VB is larger than the first voltage VA; a differential multi-level converter comprising a differential decoupling capacitor CD coupled between terminals (or points) at which exist respective ones of the first and second voltages VA, and VB; a differential multi-level converter configured such that: (1) the output is taken with discrete levels; and (2) a dc input voltage is taken differentially between the first and second voltages VA and vB rather than from an input source and common; a differential multi-level converter configured such that the output voltage output VSM is a ground referenced output voltage vSM which may take on discrete voltage values distributed between the first and second voltage values VA and VB, with energy transferred from and between terminals at which VA and VB exist and the of the output differential multi-level converter; a differential multi-level converter having switches (e.g., SA, SA′, SB, SB′) which are all NMOS devices; a differential multi-level converter having switches (e.g., SA, SA′, SB, SB′) comprising a combination of NMOS and PMOS devices; a differential multi-level converter having switches (e.g., SA, SA′, SB, SB′) comprising all PMOS devices; differential multi-level converter comprising a pair of switches implemented as a CMOS pair; a differential multi-level converter having a first pair of switches implemented as a CMOS pair and a second pair of switches implemented as a CMOS pair; a differential multi-level converter comprising switches having unidirectional blocking capability and which are required to block less than or equal to the maximum difference between the first and second voltages vA and vB but more than half the maximum difference between the first and second voltages VA, VB; a differential multi-level converter comprising switches with gate-drive levels derived from the first and second voltages VA, VB; a differential multi-level converter configured to provide four (4) switch states providing the following specified output voltage VSM:
In accordance with a still further aspect of the concepts described herein a radio frequency (rf) module includes a hybrid supply generator/modulator comprising a hybrid magnetic/switched-capacitor power converter configured to synthesize three or more discrete supply modulator voltage levels vSM at its output at substantially any instant in time. The radio frequency (rf) module may further include one or more of the following features independently or in combination with one or more other features to include: a supply modulator having voltage levels vSM based upon a pair of independently-controlled dc supply voltages synthesized from an input voltage VIN; the three or more discrete levels are related discrete voltage levels; the hybrid supply generator/modulator generates two or more regulated supply voltages and directly provides one or more additional supply voltage levels to a power amplifier; a hybrid supply generator/supply modulator which includes a multi-output regulation stage which receives, couples or otherwise receives an input voltage VIN and synthesizes two intermediate voltages VA and VB; and a multilevel converter having its input differentially connected or otherwise coupled between voltages VA and VB, the multilevel converter configured to enable synthesis of three or more instantaneous output voltage levels vSM wherein the hybrid supply generator/supply modulator is provided as integrated circuit.
In accordance with a still further aspect of the concepts described herein a system includes a differential multi-level converter; and a multi-output regulation stage having N outputs, the multi-output regulation stage comprising: N separate power converters configured to synthesize first and second voltages vA and vB wherein the first and second voltages vA and vB are coupled to respective ones of the first and second outputs of the multi-output regulation stage wherein depending upon voltage range requirements, at least one of the N separate power converters is implemented as a 4-switch buck-boost converter and at least one of the N separate power converters is implemented either as: a buck converter configured to supply the smaller of the two voltages vA and vB; or as a boost converter configured to supply the larger of the two voltages vA and vB.
According to another aspect of the present disclosure, a hybrid supply generator/modulator comprises: a multi-output regulation stage configured to receive an input voltage and synthesize two intermediate voltages having voltage levels different from each other; a multilevel converter configured to receive the two intermediate voltages at its input and provide a supply voltage having a voltage level corresponding to one of the two intermediate voltage levels or at least one synthesized voltage level different than the two intermediate voltage levels, the multilevel converter comprising at least one flying capacitor and a set of at least four switches; and at least one charge regulation circuit to control charge on the at least one flying capacitor.
In some embodiments, one of the two intermediate voltages is the input voltage. In some embodiments, the at least one flying capacitor and the set of at least four switches are collectively configured to transfer charge from the two intermediate voltages to the supply voltage.
In some embodiments, the at least one charge regulation circuit is configured to monitor a voltage of the at least one flying capacitor and to charge or discharge the at least one flying capacitor to maintain said voltage within a voltage range. In some embodiments, the charge regulation circuit includes a differential sensor configured to detect the voltage of the at least one flying capacitor. In some embodiments, the voltage range is based on a reference voltage. In some embodiments, the reference voltage is a variable voltage. In some embodiments, the reference voltage is related to the two intermediate voltages. In some embodiments, the reference voltage is derived from the two intermediate voltages. In some embodiments, the reference voltage is at a midpoint between the two intermediate voltages. In some embodiments, the at least one charge regulation circuit is configured to control the charge on the at least one flying capacitor based on a comparison involving the reference voltage and the voltage across the at least one flying capacitor. In some embodiments, the at least one charge regulation circuit is configured to control the charge on the at least one flying capacitor based on comparing a magnitude of a difference between the reference voltage and the voltage across the at least one flying capacitor to a threshold value.
In some embodiments, the at least one charge regulation circuit is configured to selectively control the charge of the at least one flying capacitor based on a state or mode. In some embodiments, the state or mode is a state or mode of the hybrid supply generator/modulator. In some embodiments, the at least one charge regulation circuit is configured to control the charge of the at least one flying capacitor during at least one of: a shutdown mode of operation; a standby mode of operation; and a startup mode of operation.
In some embodiments, the at least one charge regulation circuit comprises a linear regulator configured to receive a reference voltage and to control the charge of the at least one flying capacitor. In some embodiments, the at least one charge regulation circuit further comprises another set of at least two switches configured to selectively connect terminals of the at least one flying capacitor to the linear regulator. In some embodiments, a first one of the another set of at least two switches is connected between an output of the linear regulator and a first terminal of the at least one flying capacitor, and a second one of the another set of at least two switches is connected between the output of the linear regulator and a second terminal of the at least one flying capacitor. In some embodiments, the another set of at least two switches are configured to sink or source current through the at least one flying capacitor to maintain a voltage of the at least one flying capacitor within a voltage range.
In some embodiments, the at least one charge regulation circuit comprises: a regulator having one or more controllable source elements configured to charge and discharge the at least one flying capacitor; and a charge control circuit configured to receive a reference voltage and to control individual ones of the controllable source elements to maintain a voltage across the at least one flying capacitor to within a voltage range. In some embodiments, the one or more controllable source elements comprise one or more controllable current sources. In some embodiments, the one or more controllable source elements are configured to sink or source current through the at least one flying capacitor to maintain a voltage of the at least one flying capacitor within a voltage range.
In some embodiments, the at least one flying capacitor includes a plurality of flying capacitors, wherein the at least one charge regulation circuit comprises a plurality of charge regulation circuits each configured to control charge on a corresponding one of the plurality of flying capacitors. In some embodiments, the at least one charge regulation circuit is configured to adjust at least one of the two intermediate voltages.
According to another aspect of the present disclosure, a method is provided for controlling charge on at least one flying capacitor of a hybrid supply generator/modulator having a multi-output regulation stage and a multilevel converter, the method comprising: monitoring a voltage of the at least one flying capacitor; and charging or discharging the at least one flying capacitor to maintain said voltage within a voltage range.
In some embodiments, the monitoring of the voltage of the at least one flying capacitor comprises detecting the voltage of the at least one flying capacitor using a differential sensor. In some embodiments, the voltage range is based on a reference voltage. In some embodiments, the reference voltage is a variable voltage. In some embodiments, the reference voltage is derived from two intermediate voltages generated by the multi-output regulation stage. In some embodiments, the reference voltage is between two intermediate voltages generated by the multi-output regulation stage. In some embodiments, the charging or discharging of the at least one flying capacitor to maintain said voltage within a voltage range comprises performing a comparison involving the voltage of the at least one flying capacitor to the reference voltage. In some embodiments, the comparison comprises: calculating a difference between the reference voltage and the voltage of the at least one flying capacitor; and comparing a magnitude of the difference to a threshold value.
In some embodiments, the method further comprises: determining a mode of operation of the hybrid supply generator/modulator, wherein the charging or discharging of the at least one flying capacitor is responsive to the determined mode of operation. In some embodiments, the wherein the charging or discharging of the at least one flying capacitor is responsive to the mode of operation being at least one of: a shutdown mode of operation; a standby mode of operation; and a startup mode of operation.
In some embodiments, the charging or discharging of the at least one flying capacitor comprises operating a plurality of switches configured to selectively connect terminals of the at least one flying capacitor to a regulator. In some embodiments, the charging or discharging of the at least one flying capacitor comprises controlling one or more controllable source elements. In some embodiments, the method further comprises adjusting at least one of two intermediate voltages generated by the multi-output regulation stage using circuitry also used for the charging or discharging of the at least one flying capacitor.
According to another aspect of the present disclosure, an apparatus comprises: a multi-output regulation stage having an input to receive an input voltage and at least two outputs to provide two intermediate voltages having voltage levels different from each other; a multilevel converter having at least two inputs to receive the two intermediate voltages and provide an output voltage having a level corresponding to one of the two intermediate voltage levels or another level generated from the two intermediate voltage levels using at least one capacitor; and at least one charge regulation circuit to regulate voltage across the at least one capacitor to maintain said voltage within a range.
According to another aspect of the present disclosure, a system comprises: a hybrid supply generator/modulator having: a first stage having an input configured to receive an input voltage and first and second outputs configured to provide respective first and second intermediate voltages having respective first and second intermediate voltage levels, and a second stage having first and second inputs configured to respectively receive the first and second intermediate voltages, a switching network, at least one energy storage device, and an output configured to provide an output voltage; and a controller configured to operate the switching network to modulate the voltage level of the output voltage from among a set of three or more voltage levels.
In some embodiments, the first or second intermediate voltage corresponds to the input voltage. In some embodiments, the set of three or more voltages levels includes at least: a first voltage level corresponding to the first intermediate voltage level; a second voltage level different from the first and second intermediate voltage levels; and a third voltage level corresponding to the second intermediate voltage level. In some embodiments, the switching network has at least the following states: a first state producing the third voltage level; a second state producing the second voltage level; a third state also producing the second voltage level; and a fourth state producing the first voltage level.
In some embodiments, in response to a command to set the output voltage level to the second voltage level, the controller uses a state machine to operate the switching network alternately between the second and third states to maintain the second voltage level. In some embodiments, transitions of the state machine are based at least in part on a voltage across the at least one energy storage device. In some embodiments, transitions of the state machine are based on comparisons involving a voltage across the at least one energy storage device, the first and second intermediate voltage levels, and a threshold value.
In some embodiments, the switching network includes: a first switch having a first terminal connected to the second input of the second stage; a second switch having a first terminal connected to a second terminal of the first switch; a third switch having a first terminal connected to a second terminal of the second switch; and a fourth switch having a first terminal connected to a second terminal of the third switch and a second terminal connected to the first input of the second stage. In some embodiments, in the first state, the first and second switches are on; in the second state, the first and third switches are on; in the third state, the second and fourth switches are on; and in the fourth state, the third and fourth switches are on.
In some embodiments, a first terminal of the at least one energy storage device is connected between the first and second switches and a second terminal of the at least one energy storage device is connected between the third and fourth switches. In some embodiments, the output of the second stage is connected between the second and third switches. In some embodiments, the set of three or more voltages levels includes at least: a first voltage level corresponding to the first intermediate voltage level; a second voltage level different from the first and second intermediate voltage levels; a third voltage level also different from the first and second intermediate voltage levels; and a fourth voltage level corresponding to the second intermediate voltage level.
In some embodiments, the switching network has at least the following states: a first state corresponding to the first voltage level; a second state corresponding to the second voltage level; a third state also corresponding to the second voltage level; a fourth state corresponding to the third voltage level; a fifth state also corresponding to the second voltage level; a sixth state also corresponding to the third voltage level; a seventh state also corresponding to the third voltage level; and an eighth state corresponding to the fourth voltage level. In some embodiments, the controller uses: a first state machine to operate the switching network alternately between the second, third, and fifth states to maintain the second voltage level; and a second state machine to operate the switching network alternately between the fourth, sixth, and seventh states to maintain the third voltage level.
In some embodiments, the at least one energy storage device includes a plurality of energy storage devices, and wherein transitions of the first and second state machines are based on voltages across each of the plurality of energy storage devices. In some embodiments, transitions of the first and second state machines are based on comparisons involving voltages across one the plurality of energy storage devices, the first and second intermediate voltage levels, and threshold values.
In some embodiments, the switching network includes: a first switch having a first terminal connected to the second input of the second stage; a second switch having a first terminal connected to a second terminal of the first switch; a third switch having a first terminal connected to a second terminal of the second switch; a fourth switch having a first terminal connected to a second terminal of the third switch; a fifth switch having a first terminal connected to a second terminal of the fourth switch; and a sixth switch having a first terminal connected to a second terminal of the third switch and a second terminal connected to the first input of the second stage.
In some embodiments, in the first state, the fourth, fifth, and sixth switches are on; in the second state, the first, fourth, and fifth switches are on; in the third state, the second, fourth, and sixth switches are on; in the fourth state, the first, second, and fourth switches are on; in the fifth state, the third, fifth, and sixth switches are on; in the sixth state, the first, third, and fifth switches are on; in the seventh state, the second, third and sixth switches are on; and in the eight state, the first, second, and third switches are on.
In some embodiments, the at least one energy storage device includes first and second energy storage devices; a first terminal of the first energy storage device is connected between the second and third switches and a second terminal of the first energy storage device is connected between the fourth and fifth switches; and a first terminal of the second energy storage device is connected between the first and second switches and a second terminal of the second energy storage device is connected between the fifth and sixth switches. In some embodiments, the output of the second stage is connected between the third and fourth switches.
According to another aspect of the present disclosure, a method is provided for controlling a hybrid supply generator/modulator, the method comprising: producing control signals to turn switches of a second stage of the hybrid supply generator/modulator on and off to modulate a voltage level of a supply voltage from among a set of three or more voltage levels, wherein the hybrid supply generator/modulator comprises a first stage to generate first and second intermediate voltage levels from a first input and a second stage to synthesize the supply voltage from the first and second intermediate voltage levels.
In some embodiments, turning the switches of the second stage on and off includes using one or more state machines to alternately operate the switches between the different ones of at least four distinct switching states to maintain at least one of the set of three or more voltage levels. In some embodiments, transitions of the one or more state machines are based on a voltage across at least one energy storage device of the second stage. In some embodiments, transitions of the one or more state machines are based on comparisons involving a voltage across the at least one energy storage device, the first and second intermediate voltage levels, and at least one threshold value. In some embodiments, the one or more state machines include at least two state machines, and wherein transitions of the state machine are based on comparisons involving a voltage across the at least one energy storage device, the first and second intermediate voltage levels, and at least two threshold values.
According to another aspect of the present disclosure, a hybrid generator/modulator comprises: a regulation stage having a single input and at least two outputs, the regulation stage configured to receive an input voltage at the single input and to provide two intermediate voltages at respective ones of the at least two outputs; and a multilevel converter configured to receive the two intermediate voltages and provide an output voltage having a voltage level corresponding to a voltage level of one of the two intermediate voltages or at least one other voltage level synthesized from the two intermediate voltages.
In some embodiments, the regulation stage comprises a converter with a single input and more than one output and a single inductive element. In some embodiments, the regulation stage comprises: a first decoupling capacitor connected to a first one of the at least two outputs; and a second decoupling capacitor connected to a second one of the at least two outputs. In some embodiments, the regulation stage further comprises a differential decoupling capacitor connected across the at least two outputs.
In some embodiments, the regulation stage comprises two converters to provide respective ones of the two intermediate voltages. In some embodiments, at least one of the two converters is a buck-boost converter. In some embodiments, at least one of the two converters is a buck converter. In some embodiments, at least one of the two converters is a boost converter. In some embodiments, at least one of the two converters comprises at least two switches and at least one inductive element.
In some embodiments, the regulation stage comprises: at least on inductive element; a first switch connected between the single input and the at least one inductive element; a second switch connected at one end between the first switch and the at least one inductive element and at another end to ground; a third switch connected between the at least one inductive element and a first one of the at least two outputs; and a fourth switch connected at one end between the fourth switch, the at least one inductive element, and the third switch, and at another end to a second one of the at least two outputs. In some embodiments, the regulation stage further comprises a fourth switch connected at one end between the at least one inductive element and the third switch and at another end to ground. In some embodiments, the hybrid generator/modulator further comprises two additional switches configured to enable direct energy transfer between the at least two outputs.
In some embodiments, the regulation stage comprises: a first converter configured to generate a first one of the two intermediate voltages; and a second converter configured to generate a second one of the two intermediate voltages, wherein the first and second converters are in a cascade arrangement. In some embodiments, the regulation stage wherein the second converter is powered by the first one of the two intermediate voltages generated by the first converter. In some embodiments, the second converter is a buck converter. In some embodiments, a voltage level of the first one of the two intermediate voltages is greater than a voltage level of the second one of the two intermediate voltages.
In some embodiments, the regulation stage comprises: a direct connection between the single input is and a first one of the at least two outputs; and a first regulator coupled between the single input is and a second one of the at least two outputs. In some embodiments, the first regulator comprises a buck converter. In some embodiments, the first regulator comprises a boost converter.
According to another aspect of the present disclosure, a system comprises: a regulation stage having at least one output coupled to an input via one or more converters, the regulation stage configured to receive an input voltage at a single input and to provide at least one intermediate voltage at the at least one output; and a multilevel converter configured to receive two intermediate voltages including the at least one intermediate voltage provided by the regulations stage and to provide an output voltage having a voltage level corresponding to a voltage level of one of the two intermediate voltages or at least one other voltage level synthesized from the two intermediate voltages.
According to another aspect of the present disclosure, a system comprises: a hybrid supply generator/modulator comprising: an input to receive an input voltage; an output to provide a modulated voltage; a multi-output regulation stage configured to provide two intermediate voltages having voltage levels different from each other, at least one of the two intermediate voltages synthesized from the input voltage; and a multilevel converter configured to receive the two intermediate voltages and to generate the modulated voltage having a voltage level corresponding to one of the two intermediate voltage levels or at least one synthesized voltage level different from both intermediate voltage levels; and circuitry coupled to the output of the hybrid supply generator/modulator and to a power supply terminal of at least one radio frequency (rf) amplifier, the circuitry configured to modify the modulated voltage supplied to the at least one rf amplifier.
In some embodiments, the circuitry comprises a disconnect switch configured to selectively supply a zero voltage level to the at least one rf amplifier. In some embodiments, the circuitry comprises a disconnect switch configured to selectively isolate the output of the hybrid supply generator/modulator from the at least one rf amplifier. In some embodiments, the disconnect switch is configured to be actuated in conjunction with enabling or disabling the rf amplifier.
In some embodiments, the circuitry comprises a pulse shaping network (PSN) configured to filter the modulated voltage. In some embodiments, the PSN includes at least one passive element. In some embodiments, the at least one passive element is realized as a discrete element. In some embodiments, the at least one passive element is realized on an integrated circuit (IC) or module. In some embodiments, the at least one passive element results from parasitic resistance, inductance, or capacitance. In some embodiments, the PSN includes: first and second inductors connected in series between the output of the hybrid supply generator/modulator and the power supply terminal of the at least one rf amplifier; a capacitor having a first terminal connected between first and second inductors; and a third inductor connected between a second terminal of capacitor and ground.
In some embodiments, the PSN includes: a resistor having a first terminal connected to the output of the hybrid supply generator/modulator; and a capacitor having a first terminal connected to a second terminal of the resistor and a second terminal connected to ground. In some embodiments, the PSN includes: a capacitor having a first terminal connected to the output of the hybrid supply generator/modulator and a second terminal connected to ground; and a resistor having a first terminal connected to the first terminal of the capacitor.
In some embodiments, the circuitry further comprises a switching network. In some embodiments, the switching network is configured such that in a first state, the switching network provides a first signal path having a first filter configuration between the output of the hybrid supply generator/modulator and the power supply terminal of the at least one rf amplifier, and in a second state, the switching network provides a second signal path having a second, different filter configuration between the output of the hybrid supply generator/modulator and the and the power supply terminal of the at least one rf amplifier. In some embodiments, the switching network comprises at least one passive element having a first terminal connected to the output of the hybrid supply generator/modulator, a switching network configured such that in a first state the switching network connects a second terminal of the at least one passive element to ground, and in a second state, the switching network disconnects the second terminal of the at least one passive element from ground.
In some embodiments, the switching network is coupled in a cascaded configuration with the hybrid supply generator/modulator. In some embodiments, the switching network is coupled across the PSN and configured to selectively provide a signal path which bypasses the PSN. In some embodiments, the switching network is coupled in parallel with a passive element of the PSN and configured to alter a transfer function of the PSN by selectively shorting at least one passive element. In some embodiments, the switching network comprises plurality of switches and at least a first set of the plurality of switches are located on a first integrated circuit die and at least a second set of the plurality of switches are located on a second, different integrated circuit die.
According to another aspect of the present disclosure, a system comprises: a hybrid supply generator/modulator comprising: an input to receive an input voltage; an output to provide a modulated voltage; a multi-output regulation stage configured to provide two intermediate voltages having voltage levels different from each other, at least one of the two intermediate voltages synthesized from the input voltage; and a multilevel converter configured to receive the two intermediate voltages and to generate the modulated voltage having a voltage level corresponding to one of the two intermediate voltage levels or at least one synthesized voltage level different from both intermediate voltage levels, wherein the output of the hybrid supply generator/modulator is directly or indirectly coupled to a power supply input of at least one radio frequency (rf) amplifier.
According to another aspect of the present disclosure, a method is provided for change a frequency response of circuit coupled to an output of a hybrid supply generator/modulator and to a radio frequency (rf) amplifier, the method comprising: in a first state, configuring the circuit to provide a first signal path having a first filter configuration between the hybrid supply generator/modulator output and the rf amplifier input; and in a second state, configuring the circuit to provide a second signal path having a second, different filter configuration between the hybrid supply generator/modulator output and the rf amplifier input.
According to another aspect of the present disclosure, a hybrid generator/modulator comprises: a regulation stage configured to provide two intermediate voltages having voltage levels different from each other, at least one of the two intermediate voltages synthesized from an input voltage; and a plurality of multilevel converters each configured to selectively output three or more instantaneous output voltage levels from the two intermediate voltages for supplying one or more power amplifiers (PAs).
In some embodiments, at least two of the plurality of multilevel converters are used to produce a supply voltage provided to at least one of the one or more PAs. In some embodiments, outputs of the at least two of the plurality of multilevel converters are combined via a combiner circuit to produce said supply voltage. In some embodiments, the combiner circuit comprises a coupled magnetic structure. In some embodiments, the combiner circuit comprises a first winding connected at a first end to the output of the first of the at least two of the plurality of multilevel converters; and a second winding connected at a first end to the output of the second of the at least two of the plurality of multilevel converters. In some embodiments, the first and second windings have equal numbers of turns. In some embodiments, the combiner circuit comprises one or more inductors. In some embodiments, the combiner circuit comprises at least one of: an interphase transformer combiner; uncoupled magnetics; a transmission-line transformer combiner; and a three-port lumped or distributed passive network.
In some embodiments, at least one of the plurality of multilevel converters is coupled to a supply terminal of at least one of the one or more PAs via a filter circuit. In some embodiments, each of the plurality of multilevel converters is independently controllable. In some embodiments, one or more PAs include one or more radio frequency (rf) PAs.
According to another aspect of the present disclosure, a hybrid supply generator/modulator comprises: a regulation stage configured to provide two intermediate voltages having voltage levels different from each other, at least one of the two intermediate voltages synthesized from an input voltage; and at least two differential multilevel converters each configured to selectively output three or more instantaneous output voltage levels from the two intermediate voltages, wherein the outputs of the at least two differential multilevel converters are coupled to provide a power amplifier (PA) supply voltage; and a controller configured to independently control each of the at least two differential multilevel converters.
In some embodiments, the controller is configured to receive an input signal indicating a desired voltage level of the PA supply voltage and to provide outputs for independently commanding the instantaneous output voltage level of the at least two differential multilevel converters according to the desired voltage level. In some embodiments, the controller is configured to delay commanding one of the at least two differential multilevel converters relative to another one of the at least two differential multilevel converters such that the instantaneous output voltage levels of the at least two differential multilevel converters are different during a period corresponding to a duration of the delay. In some embodiments, the controller is configured to select the one of the at least two differential multilevel converters to delay commanding using a state machine. In some embodiments, the duration of the delay is configurable. In some embodiments, the at least two differential multilevel converters include at least a first differential multilevel converter, a second differential multilevel converter, and a third differential multilevel converter, wherein the controller is configured to delay command of the first differential multilevel converter relative to the second differential multilevel converter using a first delay duration, and to delay command of the second differential multilevel converter relative to the third differential multilevel converter using a second delay duration different from the first delay duration.
According to another aspect of the present disclosure, a method is provided for adjusting a time domain shape and frequency content of a supply voltage using two or more differential multilevel converters, the method comprising: receiving an input signal indicating a desired voltage level of the supply voltage; generating a first output to command an instantaneous output voltage level of a first one of the two or more differential multilevel converters according to the desired voltage level; and after a delay, generating a second output to command an instantaneous output voltage level of a second one of the two or more differential multilevel converters according to the desired voltage level.
In some embodiments, the instantaneous output voltage levels of the two or more differential multilevel converters are different during a period corresponding to a duration of the delay. In some embodiments, the method further comprises: changing the duration of the delay in order to adjust the time domain shape and the frequency content of the supply voltage. In some embodiments, the method further comprises: selecting which of the two or more differential multilevel converters to delay command of using state machine.
The manner and process of making and using the disclosed embodiments may be appreciated by reference to the figures of the accompanying drawings. It should be appreciated that the components and structures illustrated in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principals of the concepts described herein. Like reference numerals designate corresponding parts throughout the different views. Furthermore, embodiments are illustrated by way of example and not limitation in the figures, in which:
Referring now to
Illustrative system 10 includes a multiple output supply generator subsystem (or more simply a “supply generator”) 12 that can synthesize multiple power supply voltages V1-Vm from a single input source 11. In some examples, supply generator 12 may regulate one or more of power supply voltages V1-Vm. Supply generator 12 provides one or more of the voltages V1-Vm, to inputs of one or more supply modulators subsystems (or more simply “supply modulators”) 14a-14N of a supply modulator system 14. Supply modulators 14a-14N can switch (and ideally, rapidly switch) among the different power supply voltages provided thereto by supply generator 12 to thus provide modulated supply voltages Vsupply #1−Vsupply #N at an output thereof. Switches may be modulated sufficiently rapidly to provide a power supply voltage to the PA such that the PA can provide the required rf output envelope while maintaining high efficiency, in accordance with techniques known in the art as discrete drain modulation, envelope tracking advanced (ETA), discrete envelope tracking, and digital envelope tracking (digital ET). Such techniques are described, for example, in one or more of U.S. Pat. Nos., 8,829,993; 9,160,287; 9,166,536; 9,172,336; 9,209,758; 9,755,672. The supply voltage inputs may be coupled to supply terminals of respect ones of one or more PAs 18a-18N. In some examples, PAs 18a-18N may be provided as rf power amplifiers. In some examples, supply generator 12 may supply the same or different voltages to supply modulators 14. In some examples, supply generator 12 a different number of voltages may be coupled between supply generator 12 and supply modulators 14.
In some examples, some or all of the supply voltages may be coupled to the supply terminals of the PAs through respective ones of optional filtering or voltage regulation stages 16a-16N. The filtering/regulation stages 16a-16N may comprise filtering networks, including passive filters and/or active filters and/or additional means of regulating the voltage (e.g., including low-dropout regulator(s), LDOs) to the PA, Vsupply, from the modulated voltage, Vmod.
In some examples, one, some or all of the supply modulator subsystems 14a-14N may comprise one or more switches to couple one or more voltages provided by supply generator 12 to PA supply terminals 19a-9N. A variety of different switching circuits (i.e. switches having a wide a variety of switch configurations or switch topologies) may be utilized to realize supply modulator subsystems 14. For example, a supply modulator subsystem may comprise a plurality of serially coupled switches configured to provide a “series” modulator. Alternatively, a supply modulator subsystem may comprise a plurality of parallel coupled switches configured to provide a “parallel” modulator. Alternatively still, a supply modulator subsystem may comprise one or more serially coupled switches and one or more parallel coupled switches.
It is appreciated that the manner in which the voltages are synthesized by the supply generator affects the required ratings of the switches in the one or more supply modulators 14a-14N. This can be an important consideration as the required voltage ratings of the modulator switches can influence (and in some cases, highly influence) switching speed (and achievable modulation rate) and modulator efficiency, both of which are significant system factors. Regardless of the modulator switch topology used, if there are m supply levels ordered in increasing voltage V1, . . . , Vm (i.e. V1<V2< . . . <Vm), the plurality (or chain) of switches coupled between the jth supply voltage Vj and the output Vmod may ideally be rated to block at least a negative voltage of magnitude (Vm−Vj) and a positive voltage that is either (Vj− V1) or Vj depending upon whether the modulator sources a lowest voltage V1 or should ideally be able to directly supply zero volts to the PA. In some examples having designs of the latter type, where the power supply provided to the PA needs to be “cut off” (discharged to a zero volt power supply), a separate low-frequency “turn-off” or “disconnect” switch can be advantageously placed in series with the output of a supply modulator capable of sourcing modulator output voltages V1, . . . , Vm. Such a turn-off switch can reduce the modulator switch chain voltage blocking requirements from Vj to (V1− V1); this can be advantageous for modulator design. Thus,
In some examples, an rf power amplifier system such as system 10 may comprise a “series” modulator in a form suitable for integrated circuit (IC) fabrication and for use with ratiometric supply voltages (e.g., V2=2V1, V3=3V1, V4=4V1). Such a design illustrates the impact of the supply levels on the required voltage rating of individual modulator devices; by correct selection of the level voltages, the best use of integrated CMOS processes can be made using both core devices and extended voltage devices to achieve the required voltage blocking characteristics of the modulator switch chains. Moreover, such a circuit illustrates the use of the generated levels for gate drive of the devices. This type of drive approach facilitates high efficiency and switching speed. However, to take advantage of driving the device gates between adjacent level voltages (e.g., between Vj and Vj-1), level voltages for this design should be maintained with sufficient spacing; otherwise, more sophisticated gate drive designs may be needed that can limit achievable switching performance.
As shown, a system 30 can comprise a multiple output supply generator 34 a supply modulator 36 and optional filter 38 and a PA 40 having an rf input 40a, an rf output 40b and a supply terminal 40c. In this example of
Also in the example of
In the example of
The illustrative systems illustrated in
In accordance with the concepts described herein, the inventors have recognized that the manner in which these two subsystems are best implemented (or “realized”) may depend upon the power level, voltage level and application space of the rf amplifier system. The inventors have also recognized that for many mobile applications (e.g., cell phones, smart phones, personal devices and the like), it may be desirable to monolithically integrate electronic elements of both the supply generator and supply modulator on a single semiconductor die (e.g., in a CMOS process or a BCD process). The inventors have further recognized that in some cases it may be desirable to integrate electronics for the supply generator, supply modulator(s) and PAs on a single die. In other cases (especially at high power) it may be desirable to implement the subsystems with discrete components connected on one or more printed circuit boards.
A variety of different switching circuits may be utilized to implement/realize a supply modulator subsystem. Two illustrative networks are shown in
Referring now to
Circuit 400 illustrates the impact of the supply levels on the required voltage rating of individual modulator devices; by correct selection of the level voltages, the best use of integrated CMOS processes can be made using both core devices and extended voltage devices to achieve the required voltage blocking characteristics of the modulator switch chains. Moreover, circuit 400 illustrates the use of the generated levels for gate drive of the devices (e.g., transistors). This type of drive approach can facilitate high efficiency and switching speed.
To take advantage of driving the device gates between adjacent level voltages (e.g., between Vj and Vj-1), level voltages for this design must be maintained with sufficient spacing. Otherwise, more sophisticated gate drive designs may be needed that can limit achievable switching performance. Devices, circuits and techniques described herein facilitate maintaining voltage levels that are suitable for achieving integrated circuit-based modulators and high-performance gate drives through the ability to maintain desired voltage relationships among the levels.
Supply generators can be realized through a variety of methods. For example, supply generators can be realized using multiple separate converters, multiple-output magnetic converters, multiple-output switched-capacitor converters and hybrid magnetic/switched-capacitor converters providing a ratiometric set of output voltages. A further approach is to realize a multiple-output supply generator that creates two independently controllable dc voltages (e.g., with a magnetic conversion stage) and further uses a differential capacitive energy transfer stage to realize one or more further dc supply voltages that are that ratiometrically distributed between or around the two independently controllable voltages. Each of these approaches has limitations (which some may consider substantial limitations) in terms of achievable size, cost, efficiency and/or performance (e.g., modulation bandwidth) of supply-modulated rf amplifier systems.
Use of multiple separate power converters to generate the multiple supply voltages yields a solution that is flexible, allowing each output voltage to be independently regulated to desired values independent of input voltage variations and providing the ability to continuously adjust the output voltages over time (e.g., to provide for adaptive bias of the PA). Unfortunately, this solution is inherently large and expensive, owing to the large numbers of physically large power supply components (e.g., magnetic components) required.
Single-inductor multiple-output converters, (sometimes referred to as “SIMO” converters) allow multiple output voltages to be independently regulated while only requiring a single magnetic component, somewhat mitigating the size challenge of multiple power converters. However, as SIMO designs inherently utilize time-sharing of the inductor to supply the multiple outputs, performance and efficiency can degrade and control complexity can increase with increasing numbers of outputs. This characteristic can limit the efficacy of this approach in multilevel supply modulator systems, which typically utilize between three and seven supply levels to achieve high performance (with even more levels potentially desirable in some cases).
Some types of converters, such as conventional multiple-output magnetic converters (e.g., multi-output flyback converters), multiple-output switched-capacitor converters and hybrid magnetic/switched-capacitor converters yield multiple ratiometrically related output voltages while reducing the numbers of magnetic components required as compared to using multiple independent power converters. Traditional multiple-output magnetic converters typically utilize transformers with scaled turns ratios to generate multiple (ideally) ratiometrically scaled output voltages. These designs can only usually regulate a single output, with the ratiometric relations of the other outputs approximately maintained by the transformer turns ratios (unless additional “post regulation” is provided the other outputs, such as through use of added linear regulators). The use of transformers tends to lower achievable efficiency in these designs (often to unacceptable levels), and such designs may suffer significant cross regulation among the outputs in practice (i.e., one output voltage varying depending upon the load on a different output). This results in undesirable performance in rf amplifier systems unless additional post regulation is used, which can further degrade performance.
Multiple-output switched-capacitor converter circuits can generate multiple ratiometrically related output voltages while achieving very high efficiency and small size, with the rational (ideal) ratios among output voltages determined by the circuit topology and/or switching pattern. However, with this type of circuit, the output voltages are all scaled versions of the input voltage, which does not provide a means to continuously regulate the output voltages independent of variations in the input voltage; this is a significant disadvantage in many systems.
Some limitations of these previous approaches to multiple-output supply generation can be addressed via hybrid magnetic/switched-capacitor circuits having ratiometrically scaled outputs. In these designs, a magnetic regulation stage independently regulates a single output voltage (independent of the system input voltage) with additional ratiometrically-related output voltages synthesized and enforced through the action of a switched-capacitor voltage balancer stage. For example, in an m-output supply generator, the magnetic stage may take an input voltage VX and regulate a single output voltage VY, with the switched capacitor voltage action synthesizing (ideally) voltages k1−VY, k2−VY, . . . , km-1−VY, where constants k1, . . . , km-1 are rational numbers determined by the circuit topology and/or switching pattern. Advantages of this approach include relatively high efficiency and small size requirements for synthesizing multiple related output voltages and relative simplicity of control.
Merits of the above design approaches notwithstanding, all designs yielding ratiometric supply generator voltage outputs have limitations (which some may consider significant limitations) for PA systems utilizing multiple level supply modulation.
One limitation of ratiometric outputs relates to the usable supply voltage ranges for available PAs. Some PAs may function well with wide supply voltage ranges of up to 4:1 or even larger (e.g., function well across a power supply voltage range from a maximum voltage of Vmax down to a minimum voltage equal to or less than Vmin=Vmax/4.) Many other PAs—including those typically used in applications such as Wi-Fi, mobile handset, and MIMO transmitters for LTE and 5G applications—can only operate over much narrower supply voltage ranges (e.g., 3:1 or even less). With ratiometric supply voltages, if the maximum voltage generated is reduced (e.g., for conditions of reduced average PA output power) then the synthesized ratiometric voltages are all reduced proportionately. This often means that one or more of the lowest synthesized voltages will become unusable for supply modulation under such conditions, as they fall below the allowed minimum PA power supply voltage. This in turn reduces the achievable PA efficiency enhancement that can be provided through supply modulation under these conditions. In many applications, it would be desirable if the power supply voltages were not maintained as a fixed set of ratios, such that all (or nearly all) of the synthesized supply voltage levels remained above the allowed minimum voltage for the PA under reduced power operation.
Another limitation of ratiometric outputs relates to how the spacing between voltages varies as the largest supply voltage synthesized is reduced. In a ratiometric-output supply generator, two adjacent voltages may be expressed as kj−VY and kj-1−VY, where k is a scaling value, j is an integer index, V is a voltage and Y is an index corresponding to the number of voltage levels, VY is the Yth voltage level and where the value of VY may be scaled up or down as the average transmit power of the PA is adjusted. The difference between voltage levels may thus be expressed as (kj−kj-1)−VY which scales up and down proportional to VY. As described above in conjunction with
For PA architectures using supply modulation, it may be desirable to provide a system that provides both very rapid variations in modulated power supply voltage (e.g., among multiple discrete levels) while also providing the ability to slowly adapt the voltages of the discrete levels over a desired range.
In particular, and as previously discussed, it would be useful to be able to efficiently and compactly generate a set of m discrete levels for supply to a PA, with two of the m voltage levels being independently controllable and the other m−2 voltage levels distributed in a prescribed relation to the two independently-controlled levels.
While not quite as flexible as truly independent control of all voltages, one would gain most of the practical benefits available from supply modulation (e.g., in terms of PA efficiency) while avoiding the above-described limitations associated with providing truly independent voltage level control or ratiometric levels. Such a design would provide significant advantages in combinations of size, cost, efficiency and performance as compared to existing approaches.
It would be further beneficial if one only need generate two regulated supply voltages and be able to directly provide one or more additional supply voltage levels to the PA, without the necessity of having a separate supply generator element to generate these additional levels cascaded with a supply modulator to select among the levels. Merging the functions of intermediate level generation and supply modulation can reduce the number and size of passive components (e.g., capacitors) required as well as the number, required area and loss of semiconductor elements (e.g., switches).
Referring now to
Of note, “hybrid magnetic/switched-capacitor converters” are a broad class of converters. Disclosed systems described as “hybrid supply generator/modulator” may be considered a specific and subtype of this broad class. Also of note, in the term, “hybrid magnetic/switched-capacitor converters,” the word “hybrid” refers to hybridization of a magnetic converter and a switched-capacitor converter together. In contrast, in the term “hybrid supply generator/modulator,” the word “hybrid” refers to hybridization of the supply generator and supply modulator.
As shown in the figure, system 500 can optionally include additional circuitry 506 coupled between an output of the hybrid supply generator/modulator 502 and the PA 504. Additional circuitry 506 may comprise, for example, a disconnect switch, filtering network(s) including passive filters and/or active filters, low-dropout regulator(s), LDO(s), and/or additional means of regulating or controlling the PA supply voltage, Vsupply, from the modulated voltage, Vsm. In some embodiments, additional circuitry 506 can have more than two terminals. For example, additional circuitry 506 can optionally be connected to ground, as shown.
System 500 can also include one or more controllers 550 to operate switches and/or other devices of hybrid supply generator/modulator 502 using control techniques described in detail below. For example, the one or more controllers 550 can implement, execute, or otherwise utilize one or more state machines described herein for modulating Vsm. In some embodiments, the hybrid supply generator/modulator 502 can include a multi-output regulation stage (or “first stage”) and a differential multilevel converter (or “second stage”) and the one or more controllers 550 can include at least one controller to control the switching state of the multi-output regulation stage and at least one controller to control the switching state of the differential multilevel converter. These can be the same controller or different controllers. In some embodiments, at least one of the one or more controllers 550 may be configured to receive commands for selecting/controlling a voltage level of the modulated voltage, Vsm.
In some embodiments, the one or more controllers 550 can include a digital controller configured to provide one or more control signals to one or more hybrid supply generators/modulators. In response, the hybrid supply generators/modulators can provide variable supply voltages to one or more rf amplifiers. That is, the control signals can be used to select discrete supply voltages for the amplifiers from among multiple independent supply voltages generated by the hybrid supply generator/modulators. In more detail, the control signals may be used to directly, or indirectly, operate one or more switches within the hybrid supply generator/modulator (e.g., switches within a multi-output regulation stage such as illustrated in
The filter network 522 of
In some embodiments, rf amplifier system 540 can be part of a transceiver system having a modem among other components external to the rf amplifier system. The modem or another one of the components can directly or indirectly generate control signals to cause the turn-off switch 542 to be actuated in conjunction with enabling/disabling the rf amplifier.
Illustrative hybrid supply generator/supply modulator 600 includes a multi-output regulation stage 602 and a differentially coupled multilevel converter 604.
Multi-output regulation stage 602 is configured to receive, couple, or otherwise takes an input voltage VIN and synthesizes two intermediate voltages VA and VB. In some embodiments, intermediate voltages VA and VB may be independently controllable. In some embodiments, multi-output regulation stage 602 may be provided as a magnetic or hybrid magnetic/switched-capacitor regulation stage.
Differentially coupled multilevel converter 604 has input differentially connected or otherwise coupled between intermediate voltages VA and VB and is configured to synthesize three or more instantaneous output voltage levels VSM therefrom. In some embodiments, differentially coupled multilevel converter 604 may use switched capacitors to synthesize instantaneous levels while enabling desired voltage/charge-balance on the capacitors. Differentially coupled multilevel converter 604 may be based on a differentially connected flying-capacitor multilevel converter (FCML) or on some other capacitor-based energy-transfer topology, including those in which the charge transfer requirements prevent one or more of the synthesizable levels to be continuously provided without switching of the differentially connected multilevel converter.
Multi-output regulation stage 602 and differentially coupled multilevel converter 604 can include one or more devices (e.g., switches) configured to be controlled according to one or more control techniques described in detail below.
The multi-output regulation stage 602 and/or differential multilevel converter 604 can be controlled by one or more controllers, such as the one or more controllers 550 of
The multi-output regulation stage 602 and/or differential multilevel converter 604 can be controlled by one or more controllers, such as the one or more controllers 550 of
Referring now to
As shown, additional optional switches Sopt,A and Sopt,B may be included to enable direct energy transfer from output 702a to output 702b or vice versa. Also as shown, a differential decoupling capacitor CD may be optionally included and connected across the two outputs 702a, 702b.
While the embodiment of
It will be appreciated that other like conversion approaches can be used to synthesize two independently controllable voltages VA and VB. For example, the structure of
Of note, whereas the hybrid supply generator/supply modulator 620 of
The various switches illustrated in
Differential multilevel converter 800 includes four switches SA, SB, SA′, SB′ connected in series between the two inputs 802a, 802b, and a flying capacitor Cf connected at one end between SA and SB and at the other end between SA′ and SB′. An output 804 (e.g., a terminal) can be connected between SB and SB′, as shown, to provide a modulated output voltage Vsm, which can be ground referenced for example. Converter 800 may optionally include a differential decoupling capacitor CD (not shown) coupled between inputs 802a, 802b.
The structure of converter 800 is partially similar to that of a flying capacitor multilevel converter (FCML) with distinctions that: (1) the output 804 is taken with discrete levels instead of being filtered to provide a continuously-variable output; and (2) the dc input 802a, 802b is taken differentially between VA and VB rather than from an input source and common. The ground referenced output voltage VSM may thus take on discrete values distributed between voltage values VA and VB, with energy transferred from and between VA and VB and the output 804.
The switches SA, SB, SA′, SB′ may be implemented in a variety of manners with some or all of the switches having unidirectional blocking capability. For example, one or all of the switches may be configured to block less than or equal to the maximum difference between VA and VB, but more than half the maximum difference therebetween.
In a CMOS or BCD process, one or more of the switches SA, SB, SA′, SB′ may be realized as all NMOS devices or a combination of NMOS and PMOS devices, or all as PMOS devices. In some implementations one may choose to implement switches SA and SA′ as a CMOS pair and switches SB and SB′ as a CMOS pair. Selection of a particular implementation may be based on size/performance of the switches and/or gate drive convenience of the switches, with gate-drive levels optionally derived from VA and VB.
In some embodiments, the differential multilevel converter of
Table 1 shows the behavior of the differential multilevel converter of
Controlled using the switch states of Table 1, converter 800 enables three effective levels (i.e., approximate level values) to be synthesized at its output 804: VA, VB, and (VA+VB)/2. Converter 800 may thus be utilized to provide similar functionality to a 3-level supply modulator producing levels L1=VA, L3=VB, and L2=(VA+VB)/2, for example.
A benefit of the design of
In some embodiments, Vcf (the voltage across flying capacitor Cf) may be maintained near (VB−VA)/2 by appropriately selecting between states two (2) and three (3) of Table 1 when seeking to synthesize an output voltage level near (VA+VB)/2. Under a positive load current (e.g., deriving from a PA), Vcf will increase over time in state two (2) and will decrease over time in state three (3).
In some embodiments, when selecting which of states two (2) or three (3) to use to supply a voltage close to (VA+VB)/2 at the modulator output (i.e., synthesizing L2), state two (2) can be selected if Vcf falls too far below (VB−VA)/2 and state three (3) can be selected if Vcf rises too far above (VB−VA)/2, where “too far” can be defined using one or more threshold values as described below.
In some embodiments, switching between states two (2) and three (3) can be controlled on a hysteretic basis and/or with clocked switching transitions. For example, such switching can occur instantaneously when the voltage Vcf exceeds an allowed voltage deviation ΔV above or below (VB−VA)/2, or with transitions clocked, such as at a discrete supply modulation clocking rate. In some embodiments, the allowed voltage deviation ΔV value may be hardcoded in the controller, may be a programmable value of the controller, or maybe be conveyed via an external signal.
It will be appreciated that circuitry may be provided to measure/detect the voltage Vcf across the flying capacitor Cf. For example, a differential sensor (not shown) may be provided, with each of its two inputs connected to a different terminal of Cf and its output connected to the controller controlling the switch states.
Referring now to
In the example of
Such state transitions can be made on either an instantaneous or clocked basis. The allowed deviation ΔV of Vet from (VB−VA)/2 determines the maximum deviation of the L2 output voltage from (VA+VB)/2, and may be used as a fixed value or a programmable value. Reducing ΔV gives a more precise supply modulator output voltage for L2 (smaller difference between the two states synthesizing L2) but requires more frequent switching between states.
In some embodiments, state machine 900 may be re-initialized each time L2 is selected (i.e., transitioning from L1 or L3), with the initialization dependent upon voltage Vcf. For example, it may be desirable to initialize the state machine to state two 902 if Vcf<(VB−VA)/2 and to initialize the state machine to state three 903 if Vcf>(VB−VA)/2. Such a selection—or a similar one with different threshold(s)—can reduce the number of transitions required between states two (2) and three (3) to synthesize L2, and hence improve efficiency.
Turning to
In some cases, state machine 920 can be initialized (e.g., at startup/power up) to one of the states 901-904 based on a default voltage level programmed or hardcoded into controller, for example.
State machine 920 can transition between states 901-904 in response to level select commands, such as commands received from an external circuit or control unit. For example, as shown, state machine 920 can transition to state 904 when L1 is selected and can transition to state 901 if L3 when selected. When L2 is selected, state machine 920 can transition to either state 902 or state 903 depending on Vco, the voltage across the flying capacitor.
One or more system controllers (e.g., controller(s) 550 of
From
L2 state selection may additionally or alternatively be done on a clocked basis. One way to do this is, for example, to use a state machine like that in
In some embodiments, when transitioning L2 states on a clocked basis, the manner in which L2 is synthesized on each clock cycle can be updated, choosing state two (2) if Vcf<(VB−VA)/2 or state three (3) if Vcf>(VB−VA)/2, optionally using a small degree of hysteresis in the comparator upon which the decision is made. For a fully clocked selection, this approach can lead to a minimum deviation in Vsm from (VB+VA)/2 for L2, at the expense of a possibly high number of transitions to do so.
Turning to
Converter 1100 includes two (2) flying capacitors Cf1, Cf2 and three (3) complementary switch pairs S1/S1′, S2/S2′, and S3/S3′. The switch pairs can be operated (e.g., by a controller) according to eight (8) different switch states to provide four (4) effective output levels (Vsm).
A voltage Vcf1 across first flying capacitors Cf1 can be controlled to be near (VB−VA)/3 and a voltage Vcf2 across second flying capacitors Cf2 can be controlled to be near 2(VB−VA)/3, enabling one to synthesize four effective output levels:
L1=VA;
L2=VB−2(VB−VA)/3≈VA+(VB−VA)/3;
L3=VB−(VB−VA)/3≈VA+2(VB−VA)/3; and
L4=VB.
There is thus an evenly spaced distribution of effective output levels between VA and VB.
In some embodiments, switches S1, S1′, S2, S2′, S3, S3′ may be selected to have a voltage rating of more than ⅓ the maximum difference between VB and VA, but need not be rated for more than the maximum difference between VB and VA. Again, gate drive sources for the switches may be derived from input voltages VA, VB and/or flying capacitor voltages Vcf1, Vcf2.
Table 2 shows the behavior of the differential multilevel converter 1100 of
As can be seen from Table 2, there is one way to synthesize L2 (i.e., state one (1)), one way to synthesize L4 (i.e., state eight (8)), and three ways to synthesize each of the two intermediate effective output levels L2 and L3. In particular, L2 may be synthesized with states two (2), three (3), and five (5) while L3 may be synthesized with states four (4), six (6), and seven (7).
The states synthesizing each of the two intermediate effective levels each have different effects on the charging and discharging of Cf1 and Cf2. (i.e., Vcf1 or Vcf2 increasing or decreasing under load). By dynamically choosing which state is used to synthesize a desired intermediate output level, the capacitor voltages Vcf1 and Vcf2 can be maintained each near their target voltages of (VB−VA)/3 and 2(VB−VA)/3. These control selections can be done through a variety of means including through use of one or more appropriate state machines. For example, a control scheme/state machine can be selected to have Vcf1 to be maintained within a voltage ΔV1 of the target voltage (VB−VA)/3 and Vcf2 to be maintained within a voltage ΔV2 of the target voltage 2(VB−VA)/3. The values ΔV1 and ΔV2 may be hardcoded in the controller, may be programmable values of the controller, or maybe be conveyed via one or more external signals.
It will be appreciated that circuitry may be provided to measure/detect the voltage Vcf1 across flying capacitor Cf1 and the voltage Vcf2 across flying capacitor Cf2. For example, two differential sensors (not shown) may be provided, one having its inputs connected across C1 and the other having its inputs connected across C2. The outputs of both differential sensors can be connected to the controller controlling the switch states.
The illustrative state machines of
The illustrative state machines of
After reading the disclosure provided herein, those of ordinary skill in the art will appreciate that hybrid supply generator/supply modulator designs having more flying capacitors and more effective output levels can be synthesized by direct extension of the 3-level design of
In general, designs providing N effective output levels may utilize N−2 flying capacitors and N−1 complementary switch pairs (yielding up to 2(N−1) switch states that may be used for level synthesis).
It will be appreciated that additional circuitry may be used to pre-charge the flying capacitors (e.g., Cr in
In some embodiments, additional circuitry may also be provided to maintain the flying capacitor voltages to within a desired range (e.g., close to their respective target voltages) during time periods when the synthesized output levels do not provide charging/discharging control of the capacitor voltage(s), when the system is not operating (e.g., in standby mode or in startup), and/or when the voltage levels VA, VB, or their references are adjusted. Such circuitry might comprise linear circuits (e.g., current sources, linear regulators, etc.) implemented in the integrated circuit.
Converter 1300 operates from two voltages VA and VB received at inputs 1302a and 1302b, respectively. The two voltages may, for example, be synthesized by a multi-output regulation stage which may be the same as or similar to one of the multi-output regulation stages described above in conjunction with
As shown, the differential multilevel converter circuit includes a set of four switches SA, SB, SA′, SB′ connected in series between inputs 1302a, 1302b, a flying capacitor Cf1 having a first terminal connected between switches SA and SB, and a second terminal connected between switches SA‘ and SB’.
To regulate charge on the capacitor Cf1, the converter 1300 further includes charge regulation circuitry (sometimes referred to as “pre-charge” or “charge holding” circuitry). In the example of
Converter 1300 provides a ground referenced output voltage VSM taken between switches SB and SB′, as shown. The output voltage VSM may take on discrete values distributed between voltage values VA and VB, with energy transferred from and between VA and VB and the output.
The switches in
The regulator 1306 and switches SE, SF may be used to regulate the flying capacitor voltage Vcf1 to within a desired range (e.g., close to reference voltage Vp) during time periods when the synthesized output levels do not provide charging/discharging control of the capacitor voltage(s), when the system is not operating (e.g., in standby mode or in startup), and/or when the voltage levels VA, VB or their references are adjusted.
In a state where switch SA is held on, switch SF may be turned on and the regulator 1306 can sink or source current through Cf1 such that the voltage on CF is maintained close to a desired reference voltage Vp. Likewise, in a state where switch SA′ is held on, switch SE may be turned on and regulator 1306 can sink or source current through Cf1 such that the voltage on Cf1 is maintained close to the desired reference voltage Vp.
The reference voltage VP can be related to the intermediate voltages VA, VB. For example, VP can be at the midpoint between VA and VB, that is, VP=(VB+VA)/2. One could optionally create reference voltage VP through a voltage divider between VA and VB. Alternatively, the reference voltage VP may be provided externally in either analog or digital form.
Regulator 1306 may be configured to drive the voltage across Cf1 to match reference voltage VP or may be configured to act to drive the voltage across Cf1 towards VP only when the difference between VP and Vcf1 exceeds a threshold value ΔVp>0. In some embodiments, the threshold ΔVp may be selected to greater than the voltage ΔV used for selecting the switch state to synthesize the output voltage level near (VB+VA)/2.
In some embodiments, regulator 1306 (e.g., a linear regulator) may be configured to source or sink current if Vcf1 is greater than a magnitude ΔVp away from Vp. This can include a hysteretic comparison. In some examples, one comparator with hysteresis may be used. In other examples, two comparators may be used: a first comparator to detect when Vcf is greater than Vp+ΔVp and a second comparator to detect when Vcf is less than Vp−ΔVp. If the first comparator is activated, regulator 1306 may be activated to drive Vcf down. If the second comparator is activated, regulator 1306 may be activated to drive Vcf up. When the voltage is within Vp−ΔVp<Vcf<Vp+ΔVp, the regulator may not act.
In some embodiments, charge regulation circuitry (e.g., regulator 1306 and switches SE, SF) may be selectively activated and deactivated based on operating mode, modulator state, duration of a particular modulator state, etc. For example, charge regulation circuitry be selectively activated during modes such as startup and standby, or during particular states of the modulator (such as when switch SA or SA′ is active) or when particular states of the modulator are held for more than a certain duration, or when voltages VA and VB are being adjusted.
Additionally, converter 1340 of
In some embodiments, charge control circuit 1346 may be configured to charge or discharge Ccf1 if its voltage Vcf1 is more than some magnitude ΔVp away from Vp. In some examples, this may be done using two comparators: a first comparator to detect when Vcf1 is more than Vp+ΔVp and a second comparator to detect when Vcf is less than Vp−ΔVp. If the first comparator is activated, then middle current source 1348b can be activated/turned up to drive Vcf1 down. If the second comparator is activated, current sources 1348a and 1348c can be activated to drive Vcf1 up. When the voltage is within Vp−ΔVp<Vcf<Vp+ΔVp, all current sources 1348a-c can be turned off.
In some embodiments, reference input Vp can be related to the intermediate voltages VA, VB such as discussed above for
In some embodiments, current sources 1348a-c of
Similar to the charge regulation circuitry discussed above with
Also as discussed above with
Turning to
Illustrative hybrid supply generator/supply modulator 1400 includes a single multi-output regulation stage 1402 and a plurality of differentially-coupled multilevel converters 1404a, 1404b, . . . , 1404n. Multi-output regulation stage 1402 receives input voltage VIN and synthesizes two intermediate voltages VA and VB which may be independently controllable. Each of the differentially-coupled multilevel converters 1404a-n may receive the intermediate voltages VA and VB and be configured to synthesis one of three or more instantaneous output voltage levels, which voltage levels may be used to supply a corresponding one of a plurality of PAs 1406a-n.
In some embodiments, the differentially-coupled multilevel converters 1404a-n may directly provide supply voltages Vsupply1 . . . N to the PAs 1406a-n, as shown. In other embodiments, the outputs of the differentially-coupled multilevel converters 1404a-n may be filtered/regulated using additional circuitry to provide the plurality of PA supply voltages Vsupply1 . . . N. Examples of such additional circuitry are described above in the context of
Multi-output regulation stage 1402 may be the same as or similar to any of the multi-output regulation stage embodiments disclosed herein. Likewise, a given one of the differentially-coupled multilevel converters 1404a-n may be the same as or similar to that any of the differentially-coupled multilevel converter embodiments disclosed herein.
In some embodiments, multi-output regulation stage 1402 can be realized on an IC. In some embodiments, differential multilevel converters 1404-n can be realized on one or more ICs. In some embodiments, the multi-output regulation stage 1402 IC can be different from the differential multilevel converters 1404-n IC(s). In some embodiments, multi-output regulation stage 1402 and one or more differential multilevel converters 1404-n can be realized on the same IC.
Turning to
System 1440 can optionally include a filter circuit 1448 or other additional circuitry coupled between combiner circuit 1444 and PA 1446, as shown. For example, filter circuit 1448 can be configured to filter to smooth the transitions of supply voltage provided to PA 1446.
A controller 1450 can be coupled to control (e.g., independently control) switching states of the differential multilevel converters 1442a and 1442b. In some embodiments, controller 1450 may be provided as part of a hybrid supply generator/modulator that also includes differential multilevel converters 1442a, 1442b. For example, controller 145 may be implemented on the same IC as converters 1442a, 1442b.
It should also be appreciated that combiner circuit 1444 may be provided as any means capable of combing two or more modulated power supply output signals provided thereto so as to provide a combined modulated signal appropriate for use in an application of interest. Examples of such combining means are provided below. After reading the disclosure provided herein, one of ordinary skill in the art will appreciate how to select or design a means for combining appropriate for use in a particular application.
In the illustrative embodiment of
Combiner circuit 1444 is not limited to interphase transformer combiners. It may comprise, for example, uncoupled magnetics (e.g., separate inductors or uncoupled windings on a single core structure), a transmission-line transformer combiner, a lumped or distributed GF combiner or hybrid circuit, or another three-port lumped or distributed passive network.
Also, while two converters 1442a, 1442b and a two-way combiner are shown in the example of
Two or more multilevel converters may be used together to provide a single output VSM. One such technique that can be used with illustrative system 1440 is so-called “split pulse transitions” (SPT). With SPT, controller 1450 can receive a controller input signal indicating a voltage level desired at the combiner output VSM, and produce outputs which are, in turn, inputs to the differential multi-level converters. Controller 1450 can independently command the output voltage level VSMA and VSMB of two multilevel converters 1442 and, thus, VSM, based on the desired voltage level indicated by the controller input signal. One skilled in the art may appreciate that more than two differential multilevel converters may be combined in similar fashion to implement SPT.
In some embodiments, controller 1450 may be configured to delay the output signal for converter 1442b or converter 1442a such that a transition observed at VSMA occurs after the same transition occurred at VSMB. This delay may be referred to as a “split pulse transition delay” or “SPT delay.” In this case, voltages VSMA and VSMB may be unequal for a period of time corresponding to the SPT delay. Controller 1450 can apply the SPT delay to either converter 1442b or converter 1442a according to a state machine implemented as part of the controller. Which multi-level converter 1442b, 1442a input receives the delay may change as frequently as every transition of the desired voltage level indicated by the controller input signal.
In some embodiments, when the SPT delay is configured to a value greater than zero, the overall transition of VSM from a first level to a second level will be comprised of three voltage levels spanning three portions. During the first portion of the overall transition at VSM, both VSMA and VSMB have the same output voltage such that VSM is equal to VSMA and VSMB. During the second period the controller commands the desired transition for multilevel converter 1442a, such that VSMA transitions to the second voltage level, but 1442b output VSMB remains at the original level. During this portion current flows between the outputs of 1442a and 1442b through combiner 1444. VSM takes on a value between VSMA and VSMB proportional to the ratio of the number of turns on winding 1452a to the number of turns on winding 1452b. Assuming an equal number of turns, the voltage VSM will be (VSMA−VSMB)/2+VSMA during this second period. The controller may delay the command for 1442a or 1442b according to an internal state machine. During the final period the controller commands the desired transition for multilevel converter 1442b, such that the output of 1442a and 1442b are again equal, and VSM will be equal to VSMA and VSMB.
SPT has the effect of changing transition shape while retaining high efficiency of the hybrid supply modulator/generator. Without SPT, the voltage VSM changes quickly from a first voltage level to a second voltage level. The sample SPT implementation above reduces dv/dt (voltage slew rate) of VSM during the transition: VSM starts at the first voltage level, moves to a voltage level between the first and second voltage levels during the SPT delay time, and then moves to the second voltage level after the SPT delay time. The SPT delay duration between 1442a and 1442b changes frequency content of the output VSM, and may be configured to optimize the time domain shape and frequency domain content of VSM. A transceiver may command the controller 1450 to adjust SPT delay time to optimize RF performance for challenging operating conditions (e.g. high- or low-bandwidth transmission, stringent linearity or emissions requirements).
While
In some embodiments, a system disclosed herein (e.g., system of
Turning to
Transitions between pulses of different voltage levels (i.e., transitions from one voltage level to another) can give rise to undesired frequency components in the varying supply voltage signals. In some embodiments, such variable supply voltages can be provided to the supply/bias terminal of the amplifier through one or more pulse shaping networks (PSNs). A PSN functions to filter out or otherwise remove undesirable frequency components in a supply voltage signal (i.e., the PSN filters or shapes the trajectory of the supply voltage signal). Thus, a filtered supply voltage signal is provided to the supply terminal of the rf amplifier. In the context of
In some implementations, the switching network 1500 may be coupled in a cascaded configuration with the hybrid supply generator/modulators 1511a, 1511b. In this example embodiment, switching network 1500 comprises two inputs 1501a, 1501b coupled to outputs of respective ones of hybrid supply generator/modulators 1511a, 1511b. Hybrid supply generator/modulators (A and B) respectively supply modulated voltage signals VSMA and VSMB as inputs to the switching network 1500.
Switching network 1500 comprises a first plurality of outputs 1502a-1502N each of which may be coupled to one or more of a second plurality of rf amplifiers (not shown in
In the example embodiment of
For example, in one embodiment, two or more output ports may be coupled to provide output signals in some cases all N output signals VO1-VON may be coupled to a bias terminal (e.g., a supply terminal) of a single rf power amplifier. In other embodiments, one or more or each output signal VO1-VON may be coupled to its own, respective, rf power amplifier (i.e., a bias terminal of respective rf amplifiers). And in still other embodiments, one or more output amplifiers may be coupled to a single output terminal of switching network 1500, while other rf output amplifiers may be coupled to two or more output signals of switching network 1500.
The switches S1-S11 of switching network 1500 may be coupled to a controller (not shown) that can open and close the switches S1-S11 to control the output signals VO1-VON. In this way, the switching network 1500 can be coupled across one or more PSN (and in some cases, configured to provide a signal path which bypasses one or more of the PSN). For example, when switch S1 is closed, modulated voltage signal VSMA is coupled to output 1502a at which voltage VO1 is provided. When switch S1 is open and switches S2 and S3 are closed, modulated voltage signal VSMA is coupled through PSN 1503 (also referred to as filter network 1503) to output 1502a. And when switches S1 and S3 are open, the output signal VO1 at output 1502a is not connected to voltage signal VSMA, and may be floating or may be tied to some other potential such as ground by circuitry not shown. Thus, switches S1, S2, and S3 can be used to adaptively (or dynamically) in real time enable or disable filtering (performed by a filter network 1503) for output signal VO1. It should be appreciated that filtering circuitry may be provided in a variety of different circuit configurations to provide filter characteristics selected to meet the needs of a particular application. Taking filter network (PSN) 1503 illustrative of filter networks 1504-1510, filter network 1503 comprises one or more electronic elements. In the example of
In some embodiments, a PSN can include one or more passive elements realized as discrete elements. In some embodiments, a PSN can include one or more passive elements realized on an IC or module. In some embodiments, a PSN can include one or more passive elements resulting from parasitic resistance, inductance, or capacitance.
In some embodiments, a PSN can include a resistor having a first terminal connected to the output of the hybrid supply generator/modulator, and a capacitor having a first terminal to the second terminal of the resistor and a second terminal connected to ground. In some embodiments, a PSN can include a capacitor having a first terminal connected to the output of the hybrid supply generator/modulator and a second terminal connected to ground, and a resistor having a first terminal connected to the first terminal of the capacitor.
Whether to connect or not a given PSN (e.g., one or more of filter networks 1503, 1508, 1510, etc.) between a hybrid supply generator/modulator (e.g., one or more of hybrid supply generator/modulators 1511a, 1511b) and an output (e.g., one of outputs 1502a-1502N) may depend upon a variety of factors including but not limited to: the rf frequency band in which the RF signal provided to the RF input of the power amplifier resides; the bandwidth of the RF signal provided to the RF input of the power amplifier; peak-to-average ratio of the RF signal provided to the RF input of the power amplifier; power level of the RF signal provided to the RF input of the power amplifier; other aspects or characteristics of the RF signal to be provided to the RF input of the PA; the mode of the supply modulation (e.g., digital envelope tracking vs. average power tracking vs. fixed supply) being used; and/or by the characteristics of an operating or application scenario (e.g., observed noise or amplifier behavior) among other factors.
Similarly, when switch S4 is closed, modulated voltage signal VSMA is coupled through filter network 1504 to output 1502b at which voltage VO2 is provided. When switch S5 is closed, modulated voltage signal VSMA is coupled through filter network 1506 to output 1502c. And when switch S6 is closed, modulated voltage signal VSMB is coupled through filter network 1506 to output 1502c. Thus, switches S5 and S6 may be used to select which modulated voltage signal VSMA or VSMB (or both in parallel) is coupled to provide an output signal at output 1502c.
When switch S7 is closed, modulated voltage signal VSMB is coupled through filter network 1508 to terminal 1502d is provided. It should be appreciated that one, some or all of filters 1503-1510 may be provided as reconfigurable filters. For example, filter 1508 comprises switch S8. Switch S is configured to change the filtering parameters (or characteristics) of filter network 1508. In this case, closing switch S creates a short circuit signal path across inductor L8 thereby effectively removing inductor L8 from filter 1508, which will affect the transfer function of filter network 1508. In this way filter characteristics of filter 1508 may be changed (e.g., adaptively changed or “on-the-fly” or in real time) to suit the needs of a particular application or operating scenario. For example, it might be desirable to dynamically adjust the characteristics of the filter depending upon the rf band in which the signal will be transmitted by the power amplifier, by the bandwidth, peak-to-average ratio, power level, or other aspects of the signal to be transmitted, and by the mode of the supply modulation (e.g., digital envelope tracking vs. adaptive power tracking vs. fixed supply) being used, or by the characteristics of an operating or application scenario (e.g., observed noise or amplifier behavior) among other factors.
Switches S9, may be switched between open and closed states to selectively couple modulated voltage signal VSMB through filter 1510 to node 1512. Switches S10, S11 may be switched between open and closed states to couple node 1512 to either or both of outputs 1502N-1, 1502N at which respective ones of voltages VN−1, VN are provided. When switches S9 and S10 are closed, modulated voltage signal VSMB is coupled through filter network 1510 to output 1502N-1 at which voltage VN-1 is provided. Similarly, when switches Se and S11 are closed modulated voltage signal VSMB is coupled through filter network 1510 to node 1512 at which voltage VN may be provided. When all three switches S9, S10, and S11 are closed, modulated voltage signal VSMB is coupled through filter network 1510 to both output terminals 1502N-1 and 1502N.
The signal paths created by switches S1-S11 in
The particular manner in which the switching network 1500 is realized may depend upon the power level, voltage level and application space of the system in which the switching network is being used (e.g., an RF amplifier system). For some mobile device applications (e.g., a cellular phone, smart phone, tablet PC with cellular communication capabilities) it may be desirable to monolithically integrate electronic elements (e.g., circuit components) of both the supply generator and supply modulator and switching elements as well as portions of the ancillary circuits on a single semiconductor die (e.g., in a CMOS or BCD process) or IC. In some cases it may be desirable to integrate electronics such as the modulator(s) and switching network 1500 together with power amplifiers on a single die. Moreover, in some cases it may be advantageous to package the modulator, switches and some of the filter components within a single module and locate other filter components and the RF amplifier in a physically separated location. In still other applications it may be advantageous to package the modulator and some switches on a first die, and further switches on at least one additional die that is placed a relative distance from the first die. This second die may also contain one or more power amplifiers or be located physically close to power amplifier(s), e.g., in a module or co-located on a circuit board. In these latter cases, the switches on the first die can be used for some of the functions described above and may be placed close to one or more first filter stages, while the second die can also implement some of the functions described above and may be placed closer to one or more second filter stages. Communication lines may also be provided between the first die and the second die (or between a controller and the second die) to allow the configuration to be changed.
Although reference is sometimes made herein to particular materials, devices and/or components, it is appreciated that other materials, devices and/or components having similar functional and/or structural properties may be substituted where appropriate, and after reading the description provided herein, a person having ordinary skill in the art would understand how to select such materials, devices and/or components and incorporate them into embodiments of the concepts, techniques, and structures set forth herein without deviating from the scope of those teachings.
Various embodiments of the concepts, systems, devices, structures and techniques sought to be protected are described herein with reference to the related drawings. Alternative embodiments can be devised without departing from the scope of the concepts, systems, devices, structures and techniques described herein. It is noted that various connections and positional relationships (e.g., over, below, adjacent, etc.) are set forth between elements in the following description and in the drawings. These connections and/or positional relationships, unless specified otherwise, can be direct or indirect, and the described concepts, systems, devices, structures and techniques are not intended to be limiting in this respect. Accordingly, a coupling of entities can refer to either a direct or an indirect coupling, and a positional relationship between entities can be a direct or indirect positional relationship.
As an example of an indirect positional relationship, references in the present description to forming layer “A” over layer “B” include situations in which one or more intermediate layers (e.g., layer “C”) is between layer “A” and layer “B” as long as the relevant characteristics and functionalities of layer “A” and layer “B” are not substantially changed by the intermediate layer(s). The following definitions and abbreviations are to be used for the interpretation of the claims and the specification. As used herein, the terms “comprises,” “comprising, “includes,” “including,” “has,” “having,” “contains” or “containing,” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, a mixture, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such composition, mixture, process, method, article, or apparatus.
Additionally, the term “exemplary” is used herein to mean “serving as an example, instance, or illustration. Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms “one or more” and “one or more” are understood to include any integer number greater than or equal to one, i.e., one, two, three, four, etc. The terms “a plurality” are understood to include any integer number greater than or equal to two, i.e., two, three, four, five, etc. The term “connection” can include an indirect “connection” and a direct “connection.”
References in the specification to an “embodiment” or “embodiments” indicate that the embodiment(s) described can include a particular feature, structure, or characteristic, but every embodiment can include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
For purposes of the description hereinafter, the terms “upper,” “lower,” “right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” and derivatives thereof shall relate to the described structures and methods, as oriented in the drawing figures. The terms “overlying,” “atop,” “on top, “positioned on” or “positioned atop” mean that a first element, such as a first structure, is present on a second element, such as a second structure, where intervening elements such as an interface structure can be present between the first element and the second element. The term “direct contact” means that a first element, such as a first structure, and a second element, such as a second structure, are connected without any intermediary elements.
Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.
The terms “approximately” and “about” may be used to mean within ±20% of a target value in some embodiments, within ±10% of a target value in some embodiments, within ±5% of a target value in some embodiments, and yet within ±2% of a target value in some embodiments. The terms “approximately” and “about” may include the target value. The term “substantially equal” may be used to refer to values that are within ±20% of one another in some embodiments, within ±10% of one another in some embodiments, within ±5% of one another in some embodiments, and yet within ±2% of one another in some embodiments.
The term “substantially” may be used to refer to values that are within ±20% of a comparative measure in some embodiments, within ±10% in some embodiments, within ±5% in some embodiments, and yet within ±2% in some embodiments. For example, a first direction that is “substantially” perpendicular to a second direction may refer to a first direction that is within ±20% of making a 90° angle with the second direction in some embodiments, within ±10% of making a 90° angle with the second direction in some embodiments, within ±5% of making a 90° angle with the second direction in some embodiments, and yet within ±2% of making a 90° angle with the second direction in some embodiments.
As used herein, the terms “processor” and “controller” are used to describe electronic circuitry that performs a function, an operation, or a sequence of operations. The function, operation, or sequence of operations can be hard coded into the electronic circuit or soft coded by way of instructions held in a memory device. The function, operation, or sequence of operations can be performed using digital values or using analog signals. In some embodiments, the processor or controller can be embodied in an application specific integrated circuit (ASIC), which can be an analog ASIC or a digital ASIC, in a microprocessor with associated program memory, in a digital signal processor (DSP), and/or in a discrete electronic circuit, which can be analog or digital. A processor or controller can include internal processors or modules that perform portions of the function, operation, or sequence of operations. Similarly, a module can include internal processors or internal modules that perform portions of the function, operation, or sequence of operations of the module. A single processor or other unit may fulfill the functions of several means recited in the claims.
As used herein, the term “predetermined,” when referring to a value or signal, is used to refer to a value or signal that is set, or fixed, in the factory at the time of manufacture, or by external means, e.g., programming, thereafter. As used herein, the term “determined,” when referring to a value or signal, is used to refer to a value or signal that is identified by a circuit during operation, after manufacture.
It is to be understood that the disclosed subject matter is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The disclosed subject matter is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the several purposes of the disclosed subject matter. Therefore, the claims should be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the disclosed subject matter.
Although the disclosed subject matter has been described and illustrated in the foregoing exemplary embodiments, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the details of implementation of the disclosed subject matter may be made without departing from the spirit and scope of the disclosed subject matter.
Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.
The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to obtain an advantage.
Any reference signs in the claims should not be construed as limiting the scope.
All publications and references cited herein are expressly incorporated herein by reference in their entirety.
This application claims the benefit under 35 U.S.C. § 119 of U.S. Provisional Patent Application No. 63/510,165 filed on Jun. 26, 2023, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63510165 | Jun 2023 | US |
