Communication systems typically include a transmitter and a receiver configured to transmit and receive signals, respectively. By transmitting and receiving signals, communication systems operate to exchange information with other communication systems. As communications systems decrease in physical size, system components may be spaced in increasingly close proximity to one another. The close proximity of system components may increase the likelihood that the operation one component in the system may adversely affect the operation of another component in the system. The likelihood of adverse affects may be further increased when components operate in the same or overlapping frequency ranges.
For example, a receiver front-end may not sufficiently attenuate a signal transmitted by a transmitter in a communication system, particularly where the frequency range of the receiver front-end includes the frequency of the transmitted signal. As a result, the signal may transmit into the receiver and damage or stress the receive circuitry because of the high power levels of the signal. In addition, during transmission, the signal that couples into the receiver may create interference that causes performance degradation in the transmitter or in other components of the communication system. It would be desirable to minimize damage and performance degradation caused by transmitting signals in a communications system.
According to one exemplary embodiment, a system comprising first interface circuitry that includes a first input pad of first receiver circuitry, and control circuitry configured to operate the first interface circuitry in a first mode to prevent the first receiver circuitry from receiving a first signal using the first input pad and a second mode to allow the first receiver circuitry to receive a second signal using the first input pad is provided.
According to another exemplary embodiment, a method performed by a system that includes receiver circuitry is provided. The method comprises operating interface circuitry in a first mode to prevent the receiver circuitry from receiving a first signal using the input pad, and operating the interface circuitry in a second mode to allow the receiver circuitry to receive a second signal using the input pad.
According to a further exemplary embodiment, a communications device comprising an antenna, a mobile communications system configured to communicate with a remote host using the antenna and including receiver circuitry with interface circuitry that includes an input pad, transmitter circuitry, and control circuitry, and an input/output system configured to communicate with the mobile communications system is provided. The transmitter circuitry is configured to transmit a first signal using the antenna and the control circuitry is configured to operate the interface circuitry in a first mode to prevent the receiver circuitry from receiving the first signal using the input pad and a second mode to allow the receiver circuitry to receive a second signal from the remote host using the input pad.
According to another exemplary embodiment, a system comprising means for preventing receiver circuitry from receiving a first signal using an input pad during a first time slot, and means for allowing the receiver circuitry to receive a second signal using the input pad during a second time slot that is subsequent to the first time slot is provided.
In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.
As described herein, a mobile communication system that includes communication circuitry, such as radio-frequency (RF) circuitry, and processing circuitry is provided as shown in the embodiments of
RF circuitry 102 is configured to transmit and receive information using antenna 109. Antenna 109 is coupled, directly or indirectly, to antenna interface circuitry 108. The information may comprise voice or data communications, for example.
RF circuitry 102 includes one or more instances of receiver circuitry 114A through 114(n) configured to receive information from respective instances of filter circuitry 110A through 110(n) where n is greater than or equal to one and represents the nth instance of receiver circuitry 114 and filter circuitry 110. To receive information, an instance of receiver circuitry 114 receives an RF signal that includes information from a remote transmitter (e.g., a base station 610 as shown in
In one embodiment, respective instances of receiver circuitry 114 and filter circuitry 110 are configured to receive information from a selected frequency band, e.g., a GSM 850, a EGSM, a PCS, or a DCS band. In this embodiment, each instance of filter circuitry 110 is configured to filter an RF signal from a selected frequency band and provide the filtered RF signal to a respective instance of receiver circuitry 114. Each instance of receiver circuitry 114 amplifies a filtered RF signal from a respective instance of filter circuitry 110, converts the amplified RF signal to digital information, and provides the digital information to baseband processor circuitry 114.
In one embodiment, each instance of filter circuitry 110 includes a surface-acoustic-wave (SAW) filter (e.g., DCS SAW filter 210 or PCS SAW filter shown in the embodiment of
In one embodiment, each instance of receiver circuitry 114 amplifies the filtered RF signal, down-converts the amplified RF signal, amplifies the down-converted signal, converts the amplified down-converted signal to digital information, and provides the digital information to baseband processor circuitry 104.
RF circuitry 102 also includes one or more instances of transmitter circuitry 118A through 118(m) configured to provide information to respective instances of power amplifier circuitry 112A through 112(m) where m is greater than or equal to one and represents the mth instance of transmitter circuitry 118 and power amplifier circuitry 112. To transmit information, an instance of transmitter circuitry 118 receives information to be transmitted from baseband processor circuitry 104, generates an RF signal that includes the information, and provides the RF signal to power amplifier circuitry 112. Power amplifier circuitry 112 amplifies the RF signal and provides the amplified RF signal to antenna interface circuitry 108 for transmission by antenna 109.
In one embodiment, respective instances of transmitter circuitry 118 and power amplifier circuitry 112 are configured to transmit information using a selected frequency band, e.g., a GSM 850, a EGSM, a PCS, or a DCS band. In this embodiment, each instance of transmitter circuitry 118 is configured to generate an RF signal using a selected frequency band and provide the RF signal to a respective instance of power amplifier circuitry 112. Each instance of power amplifier circuitry 112 amplifies the RF signal in the selected frequency band and provides the amplified RF signal to antenna interface circuitry 108 for transmission by antenna 109.
Baseband processor circuitry 104 is configured to perform digital baseband processing, e.g., voice and/or data processing, on information to be transmitted by RF circuitry 102 and on information received by RF circuitry 102. Baseband processor circuitry 104 may also be configured to perform digital processing on other information that is not associated with RF circuitry 102, i.e., information that is not to be transmitted by or has not been received from RF circuitry 102.
Control circuitry 106 is configured to control the operation of the components of mobile communications system 100 including RF circuitry 102 and baseband processor circuitry 104. For example, control circuitry 106 is configured to activate and deactivate sections of baseband processor circuitry 104. Control circuitry 106 is also configured to activate and deactivate sections of RF circuitry 102 according to the mode of operation. Control circuitry 106 includes any suitable combination of hardware and/or software components to perform the functions described herein.
Control circuitry 106 is configured to provide a signal 122 to each instance of interface circuitry 116 to independently control the operation of each instance of interface circuitry 116 in at least two modes of operation, e.g., a receive mode and a transmit mode.
Interface circuitry 116 is configured to operate in at least two modes as determined by signal 122 from control circuitry 106. In a first mode of operation, e.g., the transmit mode of operation, interface circuitry 116 is configured to prevent any signals, including electrical interference, from being received by receiver circuitry 114 using the input pads. In a second mode of operation, e.g., the receive mode of operation, interface circuitry 116 is configured to provide filtered RF signals from filter circuitry 110 to receiver circuitry 114 using input pads (shown in
In one embodiment described with reference to
In operation, one or more instances of receiver circuitry 114 and corresponding filter circuitry 110 may be configured to operate in a frequency band that overlaps a frequency band of one or more instances of transmitter circuitry 118. As a result, a portion of the RF signals transmitted by transmitter circuitry 118 may pass through antenna interface circuitry 108, filter circuitry 110, and interface circuitry 116 into receiver circuitry 114. The portion of the RF signals that are received by receiver circuitry 114 may cause damage or other unintended effects on circuitry, such as low noise amplifier (LNA) circuitry, in receiver circuitry 114. In addition, the portion of the RF signals (phase-shifted and/or attenuated transmit or other signals) that are received by receiver circuitry 114 may couple into the substrate, bias circuitry, other receiver circuitry, or even transmit related circuitry resulting in performance degradation. To prevent damage or other unintended effects in system 100, interface circuitry 116 is configured to operate in at least the two modes noted above as described in additional detail with reference to
Control circuitry 106 may be configured to selectively control the operation of each instance of interface circuitry 116 in the two modes of operation. For example, control circuitry 106 may cause each instance of interface circuitry 116 to operate in the transmit mode any time that an instance of receiver circuitry 114 is not in use, e.g., in a transmit or a signal processing time slot as described in additional detail below. Control circuitry 106 may also cause fewer than all instances of interface circuitry 116 to operate in the transmit mode any various times or in various time slots. Control circuitry 106 may be further configured to selectively control the operation of each instance of interface circuitry 116 according to other conditions or according to operations of other components of mobile communications system 100.
In one embodiment, mobile communication system 100 includes a time-division-multiplexed (TDM) communication system such as a time-division multiple access (TDMA) system, a GSM system, a GPRS system, or an EDGE system. In addition, RF circuitry 102 operates according to one or more communication protocols, channels, and frequency bands (e.g., GSM 850, EGSM, PCS, and DCS). In other embodiments, mobile communication system 100 includes another type of multi-band, multi-mode communication system such as a Bluetooth, a WLAN, a WCDMA, or a CDMA2000 communication system.
In the embodiment of
In other embodiments, the transmitter circuitry may transmit information in other frequency bands such as GSM 850 or EGSM and the receiver circuitry may receive information in other frequency bands such as GSM 850 or EGSM.
Communications circuitry 202 is configured to transmit and receive information using antenna 206. Antenna 206 is coupled, directly or indirectly, to antenna switching module 204. The information may comprise voice or data communications, for example.
To transmit information, system 200 causes antenna switching module 204 to connect antenna 206 to power amplifier 208 to allow antenna 206 to transmit information provided by transmitter buffer 218 and amplified by power amplifier 208. Communication circuitry 202 is configured to receive the information to be transmitted from processing circuitry (not shown) and provide the information to transmitter buffer 218.
To receive information, system 200 causes antenna switching module 204 to connect antenna 206 to DCS SAW filter 210 or PCS SAW filter 214. If antenna 206 is connected to DCS SAW filter 210, received information is filtered by DCS SAW filter 210, passed through matching network 212, received across interface 116B, and amplified by LNA 220 for processing by communications circuitry 202. If antenna 206 is connected to PCS SAW filter 214, received information is filtered by PCS SAW filter 214, passed through matching network 216, received across interface 116A, and amplified by LNA 222 for processing by communications circuitry 202. Communication circuitry 202 is configured to down-convert amplified signals from LNAs 220 and 222, amplify the down-converted signal, convert the amplified down-converted signal to digital information, and provides the digital information to processing circuitry (not shown).
Control circuitry 106 is configured to provide signal 122A to interface circuitry 116A and signal 122B to interface circuitry 116B to control the operation of interface circuitry 116A and 116B, respectively, in at least two modes of operation, e.g., a receive mode and an transmit mode, as described above with reference to
In operation, antenna switching module 204 electrically isolates receiver circuitry during transmission of information by transmitter circuitry by selectively connecting receiver circuitry or transmitter circuitry to antenna 206. In one embodiment, antenna switching module 204 may provide approximately 20 dB of isolation from the transmitted signal to the antenna leaking back to the receive circuitry. This is illustrated as the part of the path C1 and C2 between the power amplifier 208 and the DCS SAW filter 210 and PCS SAW filter 214 respectively. This coupling mechanism inside the antenna switching module 204 is typically capacitive. In addition, DCS SAW filter 210 and PCS SAW filter 214 provide approximately 30-50 dB of isolation outside their respective frequency bands of operation, i.e., outside of the DCS and PCS frequency bands, respectively.
In the GSM/GPRS/EDGE mobile communication system, the PCS (mobile-station) transmit frequency band is 1850 MHz to 1910 MHz, and the receive frequency band is 1930 MHz to 1990 MHz. Likewise, the DCS (mobile-station) transmit frequency band is 1710 MHz to 1785 MHz, and the receive frequency band is 1805 MHz to 1880 MHz. Note that part of the PCS transmit frequency band overlaps with part of the DCS receive frequency band.
When the frequency band of a signal transmitted by transmitter circuitry does not overlap with the frequency band of receiver circuitry in system 200, system 200 sufficiently attenuates the signal to prevent adverse affects such as damage from high voltage stress or performance degradation from occurring. For example along coupling path C2, when transmitter buffer 218 and power amplifier 208 transmit +34 dBm signal in the PCS frequency band, antenna switching module 204 attenuates the signal by approximately 20 dBm to leave a +14 dBm signal. PCS SAW filter 214 further attenuates the +14 dBm signal by approximately 40 dBm, for example, to leave a signal of −26 dBm that reaches matching network 216 and LNA 222. In the embodiment of
When the frequency band of a signal transmitted by transmitter circuitry does overlap with the frequency band of receiver circuitry in system 200, however, system 200 may not sufficiently attenuate the signal to prevent adverse affects such as damage from high voltage stress or performance degradation from occurring. For example along coupling path C1, when transmitter buffer 218 and power amplifier 208 transmit +34 dBm signal in the PCS frequency band, antenna switching module 204 attenuates the signal by approximately 20 dBm to leave a +14 dBm signal. Because the DCS frequency band of DCS SAW filter 210 overlaps with the transmitted signal in the PCS frequency band, DCS SAW filter 210 may not significantly attenuate the +14 dBm signal. As a result, the +14 dBm signal may reach matching network 212 and LNA 220. In the embodiment of
In the embodiment of
To prevent damage and performance degradation of communications circuitry 202, interface circuitry 116A and 116B are each configured to operate in at least two modes as determined by signals 122A and 122B, respectively, from control circuitry 106.
In a receive mode of operation, interface circuitry 116A is configured to allow signals from matching network 216 to be provided to LNA 222 across input pads 226A and 226B. Similarly, interface circuitry 116B is configured to allow signals from matching network 212 to be provided to LNA 220 across input pads 226C and 226D. In the embodiment of
In an transmit mode of operation, interface circuitry 116A is configured to prevent signals from matching network 216 from being provided to LNA 222 across input pads 226A and 226B, e.g., signals from coupling path C2. Similarly, interface circuitry 116B is configured to prevent signals from matching network 212 from being provided to LNA 220 across input pads 226C and 226D, e.g., signals from coupling path C1. In one embodiment described with reference to
In the transmit mode of operation, interface circuitry 116A and 116B prevent signals transmitted by power amplifier 208 from damaging LNAs 220 or 222, respectively, or degrading the performance of communications circuitry 202.
Control circuitry 106 is configured to selectively control the operation of interface circuitry 116A and 116B in the two modes of operation. For example, control circuitry 106 may cause interface circuitry 116A to operate in the transmit mode any time that PCS SAW filter 214 is not connected to antenna 206 by antenna switching module 204, and control circuitry 106 may cause interface circuitry 116B to operate in the transmit mode any time that DCS SAW filter 210 is not connected to antenna 206 by antenna switching module 204.
In the embodiment of
Buffer circuitry 302 receives an instance of signal 122 from control circuitry 106 (shown in
Protection circuitry 304 receives buffered signal 306 from buffer circuitry 302 and causes one of two states of input pad 226 in response to a logic level of buffered signal 306. In one embodiment, protection circuitry 304 is also configured to provide electrostatic discharge (ESD) protection to receiver circuitry 114. To do so, protection circuitry 304 includes circuitry configured to prevent relatively large voltages or currents, e.g., from the discharge of static electricity, from causing damage to receiver circuitry 114.
Input pad 226 includes an electrically conductive structure (not shown) that is electrically connected to filter circuitry 110, receiver circuitry 114, and protection circuitry 304. In embodiments where receiver circuitry 114 is contained in a housing (not shown) such as an integrated circuit package, the electrically conductive structure may be constructed such that at least a portion of the structure is exposed outside of the housing to allow external circuitry, such as filter circuitry 110, to be electrically connected to the portion of the structure.
In operation, protection circuitry 304 is configured to operate input pad 226 in a first mode, i.e., an transmit mode, to prevent receiver circuitry 114 from receiving signals using input pad 226 and a second mode, i.e., a receiver mode, to allow receiver circuitry 114 to receive signals using input pad 226.
In the transmit mode of operation, protection circuitry 304 is configured to provide an electrical path for signals received on input pad 226 that provides a significantly lower electrical resistance than an electrical path to receiver circuitry 114. In one embodiment, protection circuitry 304 creates an electrical path between the electrically conductive structure of input pad 226 and ground, i.e., protection circuitry 304 shorts input pad 226 to ground. In another embodiment, protection circuitry 304 creates an electrical path between the electrically conductive structure of input pad 226 and a voltage supply (not shown), i.e., protection circuitry 304 shorts input pad 226 to the voltage supply. In a further embodiment, protection circuitry 304 creates an electrical path between the electrically conductive structure of input pad 226 and the electrically conductive structure of another input pad 226 in another instance of interface unit 300, i.e., protection circuitry 304 shorts input pad 226 to another input pad 226, using a shorting switch (not shown). The shorting switch may, however, cause performance degradation in receiver circuitry 114. In each embodiment, protection circuitry 304 prevents the signals from reaching receiver circuitry 114.
In the receive mode of operation, protection circuitry 304 is configured to ensure that the electrical path in protection circuitry 304 has a significantly higher electrical resistance than the electrical path between filter circuitry 110 and receiver circuitry 114. Accordingly, protection circuitry 304 allows the signals from filter circuitry 110 to reach receiver circuitry 114 using input pad 226.
Buffer circuitry 302 receives signal 122 from control circuitry 106 (shown in
Protection circuitry 304 receives buffered signal 306 from the output of inverter 404 and causes one of two states of transistor 412 in response to a logic level of buffered signal 306.
In the first state, signal 122 provides a high logic level to the gate of transistor 412 to cause transistor 412 to short input pad 226 to ground. The first state of transistor 412 corresponds to the transmit mode of operation where transistor 412 prevents receiver circuitry 114 from receiving signals using input pad 226. When a high logic level is provided to the gate of transistor 412, transistor 412 creates an electrical path to ground in the channel between the source and the drain of transistor 412 for signals received on input pad 226. In the first state, transistor 412 provides a sufficiently low resistance between the source and the drain to short input pad 226 to ground. Accordingly, protection circuitry 304 prevents signals received on input pad 226, e.g., RF signals from filter circuitry 110, from reaching receiver circuitry 114. In the first state, transistor 412 also provides ESD protection to input pad 226 by providing a path to ground for any transient voltages or signals received on input pad 226.
In the second state, signal 122 provides a low logic level to the gate of transistor 412 to cause transistor 412 to provide ESD protection to input pad 226. The second state of transistor 412 corresponds to the receive mode of operation where transistor 412 allows receiver circuitry 114 to receive signals using input pad 226. When a low logic level is provided to the gate of transistor 412, transistor 412 provides a relatively high resistance between input pad 226 and ground. Accordingly, protection circuitry 304 allows signals received on input pad 226, e.g., RF signals from filter circuitry 110, to reach receiver circuitry 114.
In the second state, transistors 412, 414, and 416 and resistive element 418 provide ESD protection to receiver circuitry 114. In response to relatively a large voltage or current on input pad 226, e.g., from the discharge of static electricity, either the relatively high resistance between input pad 226 and ground across transistor 412 or the relatively high resistance between input pad 226 and the voltage plane, Vdd, across transistor 414 is overcome to provide an electrical path to channel the large voltage or current from input pad 226 to ground or the voltage plane. Accordingly, protection circuitry 304 prevents relatively large voltages or currents from causing damage to receiver circuitry 114.
In other embodiments, transistors 412, 414, and 416 may be replaced with other types of transistors.
In one embodiment, mobile communications system 100 and mobile communications system 200 implement time-domain isolation according to a GPRS class 12 application as illustrated by the graph of
The order of the various receive, transmit, and idle slots are shown in
RF time slots 520A, 520B, 520C, 520D, and 520E coincide with receive slots 502, 504, 506, 508 and transmit slot 510 of frame 500, respectively, as shown in
As shown in
At the end of receive slot 520D, control circuitry 106 deactivates RF circuitry 102 and activates baseband processor circuitry 104. During SP time slots 530A and 530B, each instance of receiver circuitry 114 is idle and does not receive incoming RF signals. In one embodiment, control circuitry 106 provides signal 122 at a second logic level nRX, e.g., a high logic level as shown in the example of
At the end of SP time slot 530B, control circuitry 106 activates RF circuitry 102 and deactivates baseband processor circuitry 104. During RF time slot 520E, one or more instances of transmitter circuitry 118 are active to generate and transmit RF signals. During RF time slot 520E, each instance of receiver circuitry 114 is idle and does not receive incoming RF signals. Accordingly, control circuitry 106 continues to provide signal 122 at the second logic level, nRX, e.g., the high logic level as shown in the example of
At the end of RF time slot 520E, control circuitry 106 deactivates RF circuitry 102 and activates baseband processor circuitry 104. During SP time slot 530C, each instance of receiver circuitry 114 is idle and does not receive incoming RF signals, nRX. In one embodiment, control circuitry 106 continues to provide signal 122 at the second logic level, e.g., the high logic level as shown in the example of
In other embodiments, the timing of events may be altered according to any number of criteria, including the hardware utilized in conjunction with mobile communication system 100.
Input/output system 602 receives information from a user and provides the information to mobile communications system 100 or 200. Input/output system 602 also receives information from mobile communications system 100 or 200 and provides the information to a user. The information may include voice and/or data communications. Input/output system 602 includes any number and types of input and/or output devices to allow a user provide information to and receive information from mobile communications device 600. Examples of input and output devices include a microphone, a speaker, a keypad, a pointing or selecting device, and a display device.
Power supply 604 provides power to mobile communications system 100 or 200, input/output system 602, and antenna 606. Power supply 604 includes any suitable portable or non-portable power supply such as a battery.
Mobile communications system 100 or 200 communicates with one or more base stations 610 or other remotely located hosts in radio frequencies. Mobile communications system 100 or 200 transmits information to one or more base stations 610 or other remotely located hosts in radio frequencies as indicated by a signal 620. Mobile communications system 100 or 200 receives information from a base station 610 in radio frequencies as indicated by a signal 630. In other embodiments, mobile communications system 100 or 200 communicates with base stations 610 using other frequency spectra.
In the above embodiments, a variety of circuit and process technologies and materials may be used to implement communication apparatus according to the invention. Examples of such technologies include metal oxide semiconductor (MOS), p-type MOS (PMOS), n-type MOS (NMOS), complementary MOS (CMOS), silicon-germanium (SiGe), gallium-arsenide (GaAs), silicon-on-insulator (SOI), bipolar junction transistors (BJTs), and a combination of BJTs and CMOS (BiCMOS).
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.