Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57.
Ever-evolving WiFi standards continue to impose increasingly strict linearity demands on radio frequency, RF, wireless transmitters. RF power amplifiers (PA) are key components in a transmitter chain that dominates the linearity of the transmitted signal.
Error vector magnitude (EVM) forms a common measure for power amplify linearity. A degradation in the error vector magnitude, EFM is usually a result of impairments such as raw power amplifier non-linearity (AM/AM and AM-PM), noise or bandwidth limitations. Additionally, for dynamic error vector magnitude (DEVM) under bursted WiFi signal excitation there are additional sources of linearity degradation in the form of gain drift or droop and transient turn-on gain variation. A gain drift of gain droop may arise from power device heating over the length of a long burst, i.e. a burst lasting longer than 1 millisecond.
Transient turn-on gain variation has until now received little attention even though it can be a source of major error vector magnitude (EVM) degradation, in particular if the gain transient does perturb both the preamble and the payload.
In some aspects, the techniques described herein relate to a power amplification apparatus including: a power amplifier stage (PA) configured to amplify a signal received from an attenuator or from a variable gain amplifier (VGA) of the power amplification apparatus with an amplifier gain (G); and an open loop transient gain compensation circuit configured to compensate a transient turn-on gain variation of the power amplifier stage (PA) with a transient compensation current (Icomp) added to a bias current (Ibias) supplied to the attenuator or supplied to the variable gain amplifier (VGA).
In some aspects, the techniques described herein relate to a power amplification apparatus wherein the open loop transient gain compensation circuit includes a transient compensation current generator configured to generate the transient compensation current (Icomp).
In some aspects, the techniques described herein relate to a power amplification apparatus wherein the transient compensation current generator of the open loop transient gain compensation circuit includes a memory circuit with a number of registers and a bank of capacitors controlled according to settings of at least one register of the memory circuit.
In some aspects, the techniques described herein relate to a power amplification apparatus wherein the transient compensation current generator of the open loop transient gain compensation circuit is adapted to generate a transient compensation current (Icomp) with a predefined RC-time constant.
In some aspects, the techniques described herein relate to a power amplification apparatus wherein a current amplitude and a RC-time constant of the transient compensation current (Icomp) are programmable via an integrated controller of the power amplification apparatus.
In some aspects, the techniques described herein relate to a power amplification apparatus wherein the memory circuit includes a set of registers having settings adapted to select a transient compensation current (Icomp) with an associated RC-time constant to be added to the bias current (Ibias) depending on an operation mode selected from a number of operation modes.
In some aspects, the techniques described herein relate to a power amplification apparatus wherein the operation mode includes a WiFi power mode.
In some aspects, the techniques described herein relate to a power amplification apparatus wherein the power amplifier stage (PA) and the open loop transient gain compensation circuit are implemented on a power amplifier die.
In some aspects, the techniques described herein relate to a power amplification apparatus wherein an attenuation of the attenuator is modified by an attenuation bias current boosted by the transient compensation current (Icomp) generated by said transient compensation current generator during a transmission burst of the power amplification apparatus.
In some aspects, the techniques described herein relate to a power amplification apparatus wherein the transmission burst includes a preamble for setting a level of modulation followed by a payload for data transmission.
In some aspects, the techniques described herein relate to a power amplification apparatus wherein the open loop transient gain compensation circuit is adapted to compensate the transient turn-on gain variation of the power amplifier stage (PA) with the transient compensation current (Icomp) within an initial first millisecond of the transmission burst.
In some aspects, the techniques described herein relate to a wireless communication device including: an antenna configured to transmit an amplified radio frequency signal; and a power amplification apparatus configured to provide the amplified radio frequency signal to the antenna, the power amplification apparatus including a power amplifier stage (PA) adapted to amplify a signal received from an attenuator or received from a variable gain amplifier (VGA) of the power amplification apparatus with an amplifier gain (G), and an open loop transient gain compensation circuit configured to compensate a transient turn-on gain variation of the power amplifier stage (PA) with a transient compensation current (Icomp) added to a bias current (Ibias) supplied to the attenuator or supplied to the variable gain amplifier (VGA).
In some aspects, the techniques described herein relate to a wireless communication device wherein the open loop transient gain compensation circuit includes a transient compensation current generator configured to generate the transient compensation current (Icomp).
In some aspects, the techniques described herein relate to a wireless communication device wherein the transient compensation current generator of the open loop transient gain compensation circuit includes a memory circuit with a number of registers and a bank of capacitors controlled according to settings of at least one register of the memory circuit.
In some aspects, the techniques described herein relate to a wireless communication device wherein the transient compensation current generator of the open loop transient gain compensation circuit is configured to generate a transient compensation current (Icomp) with a predefined RC-time constant.
In some aspects, the techniques described herein relate to a wireless communication device wherein a current amplitude and the RC-time constant of the transient compensation current (Icomp) are programmable via an integrated controller of the power amplification apparatus.
In some aspects, the techniques described herein relate to a wireless communication device wherein the memory circuit includes a set of registers having settings adapted to select a transient compensation current (Icomp) with an associated RC-time constant to be added to the bias current (Ibias) depending on an operation mode selected from a number of operation modes.
In some aspects, the techniques described herein relate to a wireless communication device wherein the operation mode includes a WiFi power mode.
In some aspects, the techniques described herein relate to a wireless communication device wherein the power amplifier stage (PA) and the open loop transient gain compensation circuit are implemented on a power amplifier die.
In some aspects, the techniques described herein relate to a wireless communication device wherein an attenuation of the attenuator is modified by an attenuation bias current boosted by the transient compensation current (Icomp) generated by the transient compensation current generator during a transmission burst of the power amplification apparatus.
In some aspects, the techniques described herein relate to a wireless communication device wherein the transmission burst includes a preamble for setting a level of modulation followed by a payload for data transmission.
In some aspects, the techniques described herein relate to a wireless communication device wherein the open loop transient gain compensation circuit is configured to compensate the transient turn-on gain variation of the power amplifier stage (PA) with the transient compensation current (Icomp) within an initial first millisecond of the transmission burst.
In some aspects, the techniques described herein relate to a method of compensating a transient turn-on gain variation of a power amplifier stage used for amplifying a signal received from an attenuator or from a variable gain amplifier (VGA), the method including: generating a transient compensation current (Icomp) when turning-on the power amplifier stage (PA); and adding the generated transient compensation current (Icomp) to a bias current (Ibias) supplied to the attenuator to modify its attenuation or supplied to the variable gain amplifier (VGA) to modify its gain.
In some aspects, the techniques described herein relate to a method wherein the transient turn-on gain variation of the power amplifier stage (PA) is compensated by the generated transient compensation current (Icomp) within an initial first millisecond of a transmission burst.
In some aspects, the techniques described herein relate to a method wherein the transmission burst includes a preamble used for setting a level of modulation followed by a payload used for data transmission.
In the following a detailed description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein can be embodied in a multiple of different ways, for example, as defined and covered by the claims. In this description, references made to the drawings with like reference numerals can indicate identical or functionally similar elements. It should be understood that elements illustrated in the figures are not necessarily drawn to scale. Moreover it will be understood that certain embodiments can include more elements than illustrated in the drawing and/or in subset of elements illustrated in a drawing. Further, some embodiments can incorporate any suitable combination or features from two or more drawings.
In a possible embodiment, the open loop transient gain compensation, OLTGC, circuit 4 can comprise a transient compensation current generator adapted to generate the transient compensation current Icomp supplied to the attenuator, ATT, 3 as illustrated in
The transient compensation current generator of the open loop transient gain compensation circuit 4 is adapted to generate a transient compensation current Icomp with a predefined RC-time constant. In a possible embodiment a current amplitude and an RC-time constant of the transient compensation current Icomp can be programmable via an integrated controller of the power amplification apparatus 1. In a possible implementation, the memory circuit may comprise a set of registers having settings adapted to select a transient compensation current Icomp with an associated RC-time constant to be added to the bias current Ibias depending on an operation mode selected from a number of operation modes. Operation modes may comprise one or more WiFi power modes.
The power amplifier stage 2 of the power amplification apparatus 1 as illustrated in the schematic block diagrams of
In the embodiment illustrated in
The open loop transient gain compensation circuit 3 of the power amplification apparatus 1 can be adapted to compensate the transient turn-on gain variation of the power amplifier stage 2 with the transient compensation current Icomp within the initial 1 msec of the transmission burst of said power amplification apparatus 1.
The power amplification apparatus 1 as illustrated in the schematic block diagrams of
The method of compensating a transient turn-on gain variation of a power amplifier stage can be used when amplifying a signal such as an RF signal received from an attenuator or received from a variable gain amplifier.
In the illustrated embodiment of
In a first step S1, transient compensation current Icomp is generated when turning-on the power amplifier stage.
In a further step S2, generated transient compensation current Icomp is added to a bias current Ibias. The electrical bias current can be supplied to the attenuator ATT to modify its attenuation or can be supplied to the variable gain amplifier VGA to modify its gain.
In a possible embodiment the transient turn-on gain variation of the power amplifier stage is compensated by the generated transient compensation current Icomp within the initial 1 msec of a transmission burst. This transmission burst can comprise a preamble used for setting a level of modulation followed by a payload used for data transmission.
The method for compensating a transient turn-on gain variation of the power amplifier stage is provided to counteract any power amplifier turn-on transient behavior. This ultimately improves error vector magnitude EVM for short and long transmission bursts. By applying the compensating gain function to an input active attenuator as illustrated in
Using the method according to embodiments, transient gain corrections may be achieved by applying an open loop gain correction with a programmable amplitude and time constant. This gain correction can be applied during a pulse and may be triggered by a power amplifier (PA) transmit enable control signal. The transient gain impairment is dominated by a single time constant. This means that a simple RC circuit can be used to generate a required gain compensation signal. For maximum flexibility and to reduce development time, that amplitude and time constant can be made programmable via an integrated controller of the power amplification apparatus 1.
The RC current transient output is the applied in the form of a bias current boost to an active attenuator 3 or to an active variable gain amplifier 6. In a possible implementation, the attenuation of the attenuator 3 or the gain of the variable gain amplifier 6 can be modified within the first 1 msec of a transmission burst.
The transient compensation current generator of the open loop transient gain compensation circuit 4 can be implemented such as illustrated in
The transient compensation current generator the open loop transient gain compensation circuit 4 is adapted to output transient currents with a single RC-time constant. This current can be added to the bias current generated by the bias current source 5 and supplied to the attenuator 3 as shown in
The transient compensation current Icomp can be varied using several registers of the memory circuit 7. The diagram illustrated in
As can be seen in
The compensation scheme provided by the method according to some embodiments is almost insensitive to burst length variations of the transmission burst.
The method and apparatus according to embodiments provide a simple open loop gain correction scheme and is adapted to compensate power amplifier turn-on transient effects. The correction scheme can be applied to an input attenuator or to a variable gain amplifier as illustrated in
The method further provides an identification of differences in power amplifier transient turn-on time constants versus WiFi mode settings and a mode dependent RC compensation current can be applied in each operation mode. This can be achieved by providing a set of registers that can store an optimum RC-time constant current to be supplied to the active attenuator 3 or to the variable gain amplifier 6. The gain correction scheme provides an excellent EVM performance in different operation modes, in particular WiFi modes, and the power amplification apparatus 1 can be realized with a compact and cost effective footprint.
The illustrated transceiver 12 can comprise a baseband signal processor, a mixer, an analog-to-digital converter ADC. In the illustrated application circuit, the baseband signal processor of the transceiver 12 can generate an I-signal and a Q-signal which can be used to represent a sinusoidal wave or a signal of a desired amplitude, frequency and phase. For example, the I-signal can represent an inphase component of the sinusoidal wave and the Q signal can represent a quadrature component of the sinusoidal wave, which can be an equivalent representation of the sinusoidal wave. In certain implementations I and Q signals can be provided to the IQ modulator of the transceiver 12 in a digital format. The baseband processor can be any suitable processor configured to process a baseband signal. For instance, the baseband processor can include a digital signal processor, a microprocessor, a programmable core, or any combination thereof. Moreover, in some embodiments, two or more baseband processors can be included in the wireless communication device 100.
The IQ modulator of the transceiver 12 can be configured to receive the I and Q signals from the baseband processor and to process the I and Q signals to generate an RF signal. For example the IQ modulator can include digital-to-analog converter DACs configured to convert the I and Q signals into an analog format, mixers for up-converting the I and Q signals to radio frequency, and a signal combiner for combining the up-converted I and Q signals into an RF signal suitable for amplification by the power amplifier 10 comprising the power amplification apparatus 1. In certain implementations, the IQ modulator may include one or more filters configured to filter frequency content of the signals processed therein.
The power amplifier bias and control circuit 11 can receive an enable signal ENABLE from the baseband processor and the battery or power high voltage Vcc from the battery 16. The power amplifier bias and control circuit 11 can generate a bias signal for the power amplifier 10 in response to the received enable signal. The power amplifier bias and control circuit 11 can also include circuitry configured to perform dynamic error vector magnitude (DEVM) compensation in accordance with any of the principles and advantages discussed herein. For instance, the bias and control circuit 11 can compensate changes in the gain of the power amplifier 10 over temperature during a relatively long burst. The bias and control circuit 11 may include also a temperature compensation circuit.
The directional coupler 13 can be positioned between the output of the power amplifier 10 and the input of the switch module 14, thereby allowing an output power measurement of the power amplifier 10 that does not include insertion loss of the switch module 14. The directional coupler 13 can be positioned at a different point in the wireless communication device 100 in some other instances. The output signal from the directional coupler 13 can be provided to the mixer of the transceiver 12 which can multiply the sensed output signal by a reference signal of a controlled frequency so as to downshift the frequency content of the sensed output signal to generate a downshifted signal. The downshifted signal can be provided to the analog-to-digital converter ADC of the transceiver 12 which converts the downshifted signal to a digital format suitable for processing by the baseband processor of the transceiver 12. By including the feedback path between the output of the power amplifier 10 and the baseband processor, the baseband processor can be configured to dynamically adjust the I and Q signals to optimize the operation of the electronic system 100. For example, configuring the wireless communication device 100 in this manner can aid in controlling the power added efficiency PAE and/or linearity of the power amplifier 10 comprising the power amplification apparatus 1 according to some embodiments.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, novel methods, apparatuses and systems described herein may be embodied in a variety of other forms. Furthermore, various emissions, substitutions and changes in the form of the methods, apparatus and systems described herein may be made without departing from the spirit of the disclosure. For example, circuit blocks described herein may be deleted, moved, added, subdivided, combined and/or modified. Each of the circuit blocks may be implemented and varied in a variety of different ways. The accompanying claims and their equivalents are intended to cover any such forms or modifications and would fall within the scope and spirit of the disclosure.
Number | Date | Country | |
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63449669 | Mar 2023 | US |