TWI719936B - Power amplifier system, mobile device, and method for characterizing a front end module of a wireless device - Google Patents

Abstract

A power amplifier system front end measures both forward and reverse power associated with an RF transmit signal. A processor is configured to use measurements derived from the measured forward and reverse power output to adjust the RF transmit signal in order to compensate for one or more memory effects of the power amplifier system.

Description

Power amplifier system, mobile device and method for characterizing front-end module of wireless device

Incorporate by reference into any priority application

Any and all applications identified in the application data sheet for a foreign or domestic priority claim are hereby incorporated by reference in accordance with 37 CFR 1.57.

The embodiments of the present invention are related to electronic systems, and in particular to systems including power amplifiers for radio frequency (RF) electronic devices.

The mobile device may include a power amplifier to amplify an RF signal for transmission via an antenna. For example, in mobile devices with a time division multiple access (TDMA) architecture, such as the Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), and Broadband Code Division Multiple Access (W-CDMA) ) The mobile devices found in the system can use a power amplifier to amplify an RF signal with a relatively low power. The power amplifier can be included in a mobile device front-end module, which also includes a duplexer, an antenna switch module, and a coupler. Modern front-end modules can experience significant performance degradation in certain environments, including degraded linearity.

Embodiments for solving these and other problems are described herein. For example, degraded linearity can span multiple frequency bands and in multiple modes (such as an average power tracking (APT) mode, envelope tracking (ET) mode, digital predistortion (DPD) mode (e.g., fixed supply or ET DPD). It is particularly important to operate the front-end module in one or more of the modes). When a mismatch is present at the antenna, one problem is degraded linearity (for example, adjacent channel leakage ratio [ACLR]). This is especially true in the ET DPD mode when the power amplifier is driven by a broadband signal such as a 50-resource-block long-term evolution signal (50 RB LTE). In this case, for example, when a 5:1 voltage standing wave ratio (VSWR) is present at the antenna, there may be a one-tenth decibel (dB) degradation. This degradation can gradually get worse as the frequency modulation bandwidth increases. Therefore, it can be particularly beneficial to compensate for this degradation in ET and high-frequency bandwidth situations.

For example, when the system is in ET mode, the duplexer can degrade performance. For example, the inherent group delay in the duplexer together with poor matching can lead to memory effects, for example, where the system gain shape (eg, AM-AM/AM-PM) varies across the transmission RB bandwidth (ie, channel) . In addition, due to changes in the PA compression point during the mismatch period, AM-AM (amplitude-to-amplitude) and/or AM/PM (amplitude-to-phase) response changes are usually experienced across various mismatch conditions (even for narrowband signals). The typical open-loop, memoryless DPD is usually not enough to solve the gain shape change within the transmission bandwidth. Therefore, certain embodiments disclosed herein adjust the DPD of the memory or otherwise account for the memory (that is, the gain shape change across the channel) and the specific mismatch state at the antenna. In addition, the appropriate (e.g., optimal) delay applied between the modulator and the RF signal (for ET operation) also varies with the VSWR state and within the TX channel. Therefore, certain embodiments described in this article also adapt to this delay within the transmission bandwidth.

According to some aspects of the present invention, a system and method for improving the performance (for example, linearity) of a mobile device front-end module during a mismatch period is provided. The above situation can be achieved under normal conditions without incurring a large amount of additional performance or performance loss. Depending on the specific implementation, the examples provided herein can provide these benefits in the following modes: ET mode, APT mode, DPD mode, or a combination thereof (such as in a combined DPD/ET mode).

According to at least one aspect of the present invention, a power amplifier system is provided. The system includes a modulator and a front-end module configured to generate a radio frequency (RF) transmission signal. The front-end module may include a power amplifier configured to amplify the RF transmission signal to generate an amplified RF transmission signal. The front-end module may also include a coupler positioned between an antenna and the power amplifier. The coupler can be configured to output one of the forward power and reverse power measurements associated with the RF transmission signal. In some embodiments, the coupler is a two-way coupler. The system may additionally include a non-volatile memory storing an equalizer table. The equalizer table may have a plurality of entries generated during a pre-characterization period of one of the front-end modules. The system may also include a processor configured to (a) receive the voltage standing wave ratio (VSWR) measurement value derived from the forward power and the reverse power output from the coupler, (b) Access items in the equalizer table based at least in part on the VSWR measurement values, and (c) adjust the RF transmission signal based on the accessed items to compensate for one of the power amplifier systems Or multiple memory effects. For example, the system may include a digital predistortion table (DPD), where the processor is configured to adjust by adapting the values in the DPD table based on the accessed items in the equalizer table The RF transmission signal. The system may be in the form of a mobile device, which may further include an antenna configured to receive the amplified RF signal from the front-end module.

The front-end module of the power amplifier system can be configured in various ways. The equalizer table is generated by using a programmable antenna tuner in some cases, and the programmable antenna tuner is used to tune the front-end module to the desired VSWR point. In some configurations, the front-end module does not include an integrated antenna tuner. In some implementations, a programmable antenna tuner can be included in the front-end module and positioned between the antenna and the coupler. The programmable antenna tuner can be adjusted to tune an impedance experienced by the power amplifier to provide a rough nonlinear correction in the power amplifier system. The adjustment of the RF transmission signal based on the accessed items can be provided in the power amplifier system Fine nonlinear correction. The front-end module may include one or more duplexers positioned between the power amplifier and the bidirectional coupler. In some cases, the duplexer contributes to at least some of the memory effects.

The power amplifier system may additionally include an envelope tracking system configured to provide a power supply control signal to the power amplifier to control a voltage level of the power amplifier based on a shaped envelope signal. The processor is further configured in some cases to adjust a delay between the RF transmission signal and the supply control signal based on the delay value included in the accessed equalizer table entries.

According to an additional aspect of the present invention, a method of characterizing a front-end module of a wireless device is provided. The method may include: using a programmable antenna tuner to tune an impedance load at an output of a power amplifier of the front-end module so as to achieve a first characteristic state with one of a plurality of front-end module characteristic states One of the associated voltage standing wave ratio (VSWR) values. The method may also include: driving the front-end module with an RF transmission signal. The RF transmission signal may be driven according to one or more additional parameter values associated with the first characterization state. The method may further include: when the front-end module is driven by the RF transmission signal and tuned to the VSWR values, measuring one or more variables associated with the behavior of the front-end module. The one or more recorded variables may include a power amplifier compression, a maximum envelope power, and/or a delay between a power control signal of the power amplifier and the RF transmission signal. The method may also include: recording the one or more measured variables associated with the first characterization state in a table in a non-volatile memory. The steps of using, driving, measuring, and recording can be repeated for a plurality of additional characterization states of the plurality of front-end module characterization states. The programmable antenna tuner is separated from the front-end module in some cases, where the front-end module does not include an antenna tuner. The programmable antenna tuner is integrated into the front-end module in some other implementations.

According to still other aspects, a power amplifier system includes a front-end module that is configured to amplify an RF transmission signal to generate an amplified RF transmission signal A power amplifier. The front-end module may also include a programmable antenna tuner coupled to an antenna. A coupler of the front-end module can be positioned between the power amplifier and the antenna tuner, and the coupler is configured to output one of the forward power and reverse power measurements associated with the RF signal. The antenna tuner can be adjusted to tune an impedance experienced by the power amplifier to provide a coarse non-linear correction in the power amplifier system. The system may further include a non-volatile memory storing an equalizer table having a plurality of items generated during a pre-characterization period of one of the front-end modules. The system may also include a processor configured to (a) receive the voltage standing wave ratio (VSWR) measurement value derived from the forward power and the reverse power output from the coupler, and (b) at least Access items in the equalizer table based in part on the VSWR, and (c) adjust the RF transmission signal based on the accessed items. The front-end module may additionally include a duplexer in some configurations.

10‧‧‧Power Amplifier Module

11‧‧‧Wireless device

12‧‧‧RF Front End/Front End Module

13‧‧‧Transceiver

14‧‧‧antenna

15‧‧‧Transmission path

16‧‧‧Receiving path/path

17‧‧‧Power Amplifier

18‧‧‧Control components

19‧‧‧Computer readable media/computer readable memory

20‧‧‧Processor

21‧‧‧Battery

22‧‧‧Supply Control Block/Supply Control Unit

26‧‧‧Power Amplifier System

30‧‧‧Supply control driver

33‧‧‧Delay component

34‧‧‧Baseband processor

35‧‧‧Supply forming blocks or circuits

36‧‧‧Digital to Analog Converter

37‧‧‧Quadrature (I/Q) Modulator

38‧‧‧Mixer

39‧‧‧Analog to Digital Converter

40‧‧‧Digital Predistortion Meter

41‧‧‧Equalizer Table/Lookup Table/Equalizer Table

42‧‧‧Transmission Table

43‧‧‧Supply Control Table

44‧‧‧Complex Impedance Detector/Impedance Detector

45‧‧‧Front-end module

47‧‧‧Feedback signal

48‧‧‧Supply shaping branch/supply control path/envelope tracker path/supply control branch

49‧‧‧RF transmission signal

50‧‧‧Duplexer

51‧‧‧Antenna Switch Module

52‧‧‧Bidirectional Coupler/Coupler

53‧‧‧Measuring switch

54‧‧‧Integrated antenna tuner/antenna tuner

55‧‧‧Input switch

600‧‧‧Equalizer lookup table/partial table/table

602‧‧‧first column

604‧‧‧second column

650‧‧‧Partial Lookup Table/Partial Table/Table

802‧‧‧Power amplifier supply voltage

804‧‧‧RF signal

805‧‧‧Signal envelope

807‧‧‧Signal Envelope/Envelope

808‧‧‧Power amplifier supply voltage/amplifier supply voltage

810‧‧‧RF signal

814‧‧‧Power amplifier supply voltage

815‧‧‧Signal envelope

816‧‧‧RF signal

RF_IN‧‧‧RF signal

RF_OUT‧‧‧Amplified RF signal

Vcc_pa‧‧‧Power amplifier supply voltage

Figure 1 is a schematic diagram of a power amplifier module used to amplify a radio frequency (RF) signal.

Figure 2 is a schematic block diagram of an exemplary wireless device.

FIG. 3 is a schematic block diagram of an example of a power amplifier system including a transceiver and a front-end module according to some embodiments.

FIG. 4A is a schematic diagram of an embodiment of a front-end module without an integrated antenna tuner.

FIG. 4B is a schematic diagram of an embodiment of a front-end module with an integrated programmable antenna tuner.

FIG. 5 is a flowchart showing a procedure for pre-characterizing a front-end module.

6A to 6B show an example of a partial equalizer look-up table of an exemplary front-end module, showing the pre-characterized values of selected variables in different characterization states.

Figure 7A shows a process used to compensate the operation of the front-end module using the first equalizer look-up table Flow chart of the first order.

FIG. 7B shows a flowchart showing another procedure of compensating the operation of the front-end module through the combined use of coarse tuning with an integrated antenna tuner and fine tuning using an equalizer look-up table.

8A to 8C show power amplifier signals and supply waveforms for power amplifiers operating in a fixed supply voltage mode, an average power tracking mode, and an envelope tracking mode, respectively.

Fig. 9 shows an embodiment of a procedure for determining complex impedance.

The title (if any) provided in this article is for convenience only and does not necessarily affect the scope or meaning of the invention for which the patent application is filed.

FIG. 1 is a schematic diagram of a power amplifier module (PAM) 10 used to amplify a radio frequency (RF) signal. The illustrated power amplifier module 10 can be configured to amplify an RF signal RF_IN to generate an amplified RF signal RF_OUT. As explained herein, the power amplifier module 10 may include one or more power amplifiers.

FIG. 2 is a schematic block diagram of an exemplary wireless device 11 that may include one or more of the power amplifier modules 10 of FIG. 1. The wireless device 11 may include a power amplifier 17 and an RF front end 12 implementing one or more of the features of the present invention. For example, the power amplifier 17 and the RF front-end 12 are configured according to certain embodiments to compensate for non-linearity, including their non-linearity due to the memory effect caused by the impedance mismatch experienced by the power amplifier 17. In particular, the duplexer coupled to the output power amplifier 17 may include or operate as filters that add corresponding frequency response components to the system on top of other distortions, thereby forming a memory effect. For example, duplexers can exhibit uneven mismatches across transmission channels/bands, resulting in non-linear power amplifier behavior.

Such compensation may involve the use of a look-up table or other data structure, which is based on measurements taken during operation (such as voltage standing wave ratio (VSWR) measurements or power amplifiers 17 Other measured values related to the experienced complex impedance) Access the appropriate look-up table items. According to some implementations, the values in the look-up table are obtained during a characterization phase, in which a programmable antenna tuner is used to record specific variables that characterize the behavior of the system. For example, the AM-AM and/or AM-PM response curve of the power amplifier 17 can be captured across various operating states. This article will further elaborate on these technologies and associated compensations.

Although the power amplifier 17 and the RF front-end 12 are described as separate components in some cases, some or all of the power amplifiers of the power amplifier 17 may also form part of the RF front-end 12, such as where the RF front-end 12 includes a power amplifier 17 In an embodiment of highly integrated components. The combination of the power amplifier 17 and the RF front-end 12 can be collectively referred to as a front-end module.

The exemplary wireless device 11 depicted in FIG. 2 may represent a multi-band and/or multi-mode device, such as a multi-band/multi-mode mobile phone. By way of example, the Global System for Mobile Communications (GSM) standard is a digital cellular communication mode used in many parts of the world. GSM mode mobile phones can operate in one or more of the following four frequency bands: 850MHz (approximately 824MHz to 849MHz for transmission, 869MHz to 894MHz for reception), 900MHz (approximately 880MHz to 915MHz for transmission, 925MHz to 960MHz) For receiving), 1800MHz (about 1710MHz to 1785MHz for transmission, 1805MHz to 1880MHz for receiving), and 1900MHz (about 1850MHz to 1910MHz for transmission, and 1930MHz to 1990MHz for receiving). Different places in the world also use variations of the GSM frequency band and/or regional/national implementation schemes.

Code Division Multiple Access (CDMA) is another standard that can be implemented in mobile phone devices. In some implementations, CDMA devices can operate in one or more of the 800MHz, 900MHz, 1800MHz, and 1900MHz frequency bands, while certain W-CDMA and Long Term Evolution (LTE) devices can operate in, for example, about 22 Operate on two radio frequency spectrum bands.

One or more features of the present invention can be implemented in the aforementioned exemplary modes and/or frequency bands, and implemented in other communication standards. For example, 3G and 4G are non-restrictive of these standards 性例。 Sexual examples.

The illustrated wireless device 11 includes an RF front end 12, a transceiver 13, an antenna 14, a power amplifier 17, a control component 18, a computer-readable medium 19, a processor 20, a battery 21, and a supply control area Block 22.

The transceiver 13 can generate RF signals for transmission via the antenna 14. In addition, the transceiver 13 can receive incoming RF signals from the antenna 14.

It will be understood that various functionalities associated with transmitting and receiving RF signals can be achieved by one or more components collectively represented as transceiver 13 in FIG. 2. For example, a single component can be configured to provide both transmission and reception functionality. In another example, the transmission and reception functionality may be provided by separate components.

Similarly, it will be understood that various antenna functionalities associated with transmitting and receiving RF signals can be achieved by one or more components collectively represented as antenna 14 in FIG. 2. For example, a single antenna can be configured to provide both transmission and reception functionality. In another example, transmission and reception functionality may be provided by separate antennas. In yet another example, different frequency bands associated with the wireless device 11 may be provided by different antennas.

In FIG. 2, one or more output signals from the transceiver 13 are shown to be provided to the antenna 14 via one or more transmission paths 15. In the example shown, the different transmission paths 15 may represent output paths associated with different frequency bands and/or different power outputs. For example, the two exemplary power amplifiers 17 shown may represent amplifications associated with different power output configurations (eg, low power output and high power output) and/or amplifications associated with different frequency bands. Although FIG. 2 illustrates the wireless device 11 as including two transmission paths 15, the wireless device 11 may be adapted to include more or fewer transmission paths 15.

In FIG. 2, one or more detected signals from the antenna 14 are shown as being provided to the transceiver 13 via one or more receiving paths 16. In the example shown, different receive paths 16 may represent paths associated with different frequency bands. For example, the four exemplary paths 16 shown may represent the quad-band capabilities of certain wireless devices. Although Figure 2 shows the wireless device 11 is illustrated as including four receive paths 16, but the wireless device 11 may be adapted to include more or fewer receive paths 16.

To facilitate switching between receiving and transmission paths, one or more switches in the RF front end 12 may be configured to electrically connect the antenna 14 to a selected transmission or reception path. Therefore, the switch can provide numerous switching functionality associated with the operation of the wireless device 11. In some embodiments, the switch may include numerous switches that are configured to provide switching between, for example, different frequency bands, switching between different power modes, switching between transmission and reception modes, or The functionality associated with a certain combination. The switch can also be configured to provide additional functionality, including signal filtering and/or duplexing.

FIG. 2 shows that, in some embodiments, a control component 18 may be provided for controlling various control functionalities associated with the operation of the RF front-end, power amplifier 17, supply control 22, and/or other operating components. For example, the control component 18 may be included in another component (such as the transceiver 13) shown in FIG. 2 in some cases.

In some embodiments, a processor 20 may be configured to facilitate the implementation of the various processing procedures described herein. In some embodiments, the processor 20 can be operated using computer program instructions. In some embodiments, these computer program instructions can also be stored in a computer-readable memory 19, which can guide a computer or other programmable data processing equipment to operate in a specific manner. For example, for the purpose of illustration, the flowchart illustrations and/or block diagrams of methods, equipment (systems) and computer program products can also be referred to to illustrate the embodiments of the present invention. It will be understood that each block of the flowchart illustrations and/or block diagrams and combinations of blocks in the flowchart illustrations and/or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a dedicated computer, or other programmable data processing equipment to generate a machine so that the instructions (which pass through the computer or other programmable data processing equipment) The processor execution) forms a means for implementing the actions specified in the flowchart(s) and/or block diagrams.

In some embodiments, these computer program instructions can also be stored in a computer readable memory In the memory 19, the computer-readable memory 19 can guide a computer or other programmable data processing equipment to operate in a specific manner, so that the instructions stored in the computer-readable memory generate a product, and the product includes The instruction means to implement the actions specified in the flow chart(s) and/or block diagram. The computer program instructions can also be loaded into a computer or other programmable data processing equipment to cause a series of operations to be performed on the computer or other programmable equipment to generate a computer-implemented processing program, so that the The instructions executed on the computer or other programmable devices provide steps for implementing the actions specified in the flowchart(s) and/or block diagrams.

The supply control block 22 may be electrically connected to the battery 21, and the supply control block 22 may be configured to, for example, change the voltage supplied to the power amplifier 17 based on an envelope of the amplified RF signal. The battery 21 can be any suitable battery for use in the wireless device 11, including, for example, a lithium ion battery. As will be described in further detail below, by controlling the voltage level of the power amplifier supply voltage provided to the power amplifier, the power consumption of the battery 21 can be reduced, thereby improving the performance of the wireless device 11. As illustrated in FIG. 2, the envelope signal may be provided from the transceiver 13 to the supply control block 22. However, the envelope can be determined in other ways. For example, the envelope or other types of supply control signals can be determined by processing the RF signal (for example, using any suitable envelope detector to detect the envelope).

One technique for reducing the power consumption of a power amplifier is envelope tracking (ET), in which the voltage level of the power supply of the power amplifier is changed relative to the envelope of the RF signal. For example, when the envelope of the RF signal increases, the voltage level of the power supply of the power amplifier can be increased. Similarly, when the envelope of the RF signal is reduced, the voltage level of the power supply of the power amplifier can be reduced to reduce power consumption. Another form of power tracking is average power tracking (APT), in which similar to envelope tracking, the voltage level of the power supply of the power amplifier 17 is changed relative to the envelope. However, in the APT mode of operation, the power supply changes between two or more discrete values based on an average level of one of the envelopes. For example, the power level can be changed on a slot-by-slot basis, where each slot Corresponds to a different power control level. This can improve efficiency at low power and at the same time result in less power saving at a level higher than ET tracking. Another mode of power supply control is a fixed supply or direct battery connection, where the power supply to the power amplifier 17 is maintained at a fixed amount, at or above the maximum level of the envelope of the RF signal. Exemplary power and signal waveforms, average power tracking, and envelope tracking operations generated during an exemplary fixed power supply period are shown in FIGS. 8A, 8B, and 8C, respectively.

FIG. 3 is a schematic block diagram of an example of a power amplifier system 26. For example, the power amplifier system 26 may be incorporated into the wireless device 11. The illustrated power amplifier system 26 includes an RF front end 12, an antenna 14, a battery 21, a supply control driver 30, a power amplifier 17 and a transceiver 13. The illustrated transceiver 13 includes a baseband processor 34, a supply shaping block or circuit 35, a delay component 33, a digital-to-analog converter (DAC) 36, and a quadrature (I/Q) modulator 37. A mixer 38 and an analog-to-digital converter (ADC) 39. The supply shaping block 35, the delay component 33, the DAC 36 and the supply control driver 30 together form a supply shaping branch 48.

The baseband processor 34 can be used to generate an I signal and a Q signal corresponding to a sine wave or signal component of a desired amplitude, frequency, and phase. For example, the I signal can be used to represent an in-phase component of a sine wave and the Q signal can be used to represent a quadrature component of a sine wave. The I signal and the Q signal can be an equivalent representation of the sine wave. In some embodiments, the I signal and the Q signal can be provided to the I/Q modulator 37 in a digital format. The baseband processor 34 can be any suitable processor configured to process a baseband signal. For example, the baseband processor 34 may include a digital signal processor, a microprocessor, a programmable core, or any combination thereof. In addition, in some implementations, two or more baseband processors 34 may be included in the power amplifier system 26.

The I/Q modulator 37 can be configured to receive the I signal and Q signal from the baseband processor 34 and process the I signal and Q signal to generate an RF signal. For example, the I/Q modulator 37 may include a DAC configured to convert the I signal and the Q signal into an analog format for converting the I signal and the Q signal A mixer for up-converting a signal into a 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 17. In certain implementations, the I/Q modulator 37 may include one or more filters configured to filter the frequency content of the signal processed therein.

Depending on the embodiment, the supply shaping block 35 can be used to convert an envelope or amplitude signal associated with the I signal and the Q signal into a shaped power supply control signal, such as an average power tracking (APT) signal or an envelope tracking (ET) signal. )signal. Shaping the envelope signal from the baseband processor 34 can help enhance the performance of the power amplifier system 26. In certain implementations, such as where the supply shaping block is configured to implement an envelope tracking function, the supply shaping block 35 is a digital circuit configured to generate a digitally shaped envelope signal, and the DAC 36 is used It converts the digital shaped envelope signal into an analog shaped envelope signal suitable for use by the supply control driver 30. However, in other embodiments, the DAC 36 may be omitted to facilitate the provision of a digital envelope signal for the supply control driver 30 to assist the supply control driver 30 to further process the envelope signal.

The supply control driver 30 can receive a supply control signal (for example, an analog shaped envelope signal or an APT signal) from the transceiver 13 and a battery voltage V _BATT from the battery 21, and can use the supply control signal signal to generate a signal relative to the transmission The change is used for the power amplifier supply voltage V _{CC_PA} of one of the power amplifiers 17. The power amplifier 17 can receive the RF transmission signal from the I/Q modulator 37 of the transceiver 13 and can provide an amplified RF signal to the antenna 14 through the RF front end 12. In other cases, a fixed power amplifier supply voltage V _{CC_PA is} provided to the power amplifier 17. In some of these embodiments, one or more of the supply shaping block 35, the DAC 36, and the supply control driver 30 may not be included. _{Exemplary waveforms of the power amplifier supply voltage V CC_PA} and corresponding RF transmission signals for fixed supply, APT and ET power supply control operations are shown in FIGS. 8A, 8B, and 8C, respectively. In some embodiments, the power amplifier system 26 can perform two or more supply control techniques. For example, the power amplifier system 26 allows selection (for example, through firmware programming or other appropriate mechanisms) of two or more of ET, APT, and fixed power supply control modes. In these situations, the baseband processor or other appropriate controller or processor can instruct the supply shaping block 35 to enter the appropriate selected mode.

The delay component 33 implements a selectable delay in one of the supply control paths. As will be explained in further detail, the above situation can be used in some cases to compensate for other potential sources of nonlinearity and/or signal degradation. The illustrated delay element is shown in the digital domain as part of the transceiver 13 and may include a FIFO or other type of memory-based delay element. For example, however, the delay component 33 can be implemented in any suitable manner, and in other embodiments can be integrated as part of the supply shaping block 35, or can be implemented after the DAC 36 in the analog domain.

The RF front end 12 receives the output of the power amplifier 17, and may include various components, including one or more duplexers, switches (for example, formed in an antenna switch module), directional couplers, and the like. Detailed examples of compatible RF front-ends are shown and described below with respect to FIGS. 4A and 4B.

The directional coupler (not shown) in the RF front end 12 may be a bidirectional coupler or other suitable coupler or other device capable of providing a sensed output signal to the mixer 38. According to certain embodiments including the illustrated embodiments, the directional coupler can provide both the incident signal and the reflected signal (eg, forward power and reverse power) to the mixer 38. For example, the directional coupler may have at least four ports, the at least four ports including an input port configured to receive the signal generated by the power amplifier 17, an output port coupled to the antenna 14, configured to Forward power is provided to a first measurement port of the mixer 38 and configured to provide reverse power to a second measurement port of the mixer 38.

The mixer 38 can multiply the sensed output signal by a reference signal of a control frequency (not illustrated in FIG. 3) so as to shift down the frequency spectrum of the sensed output signal. The down-shifted signal can be provided to the ADC 39, and the ADC 39 can convert the down-shifted signal into a feedback signal 47 in a digital format suitable for processing by the baseband processor 34. As will be discussed in further detail As mentioned, by including a feedback path at the output of the power amplifier 17 and one of the inputs of the baseband processor 34, the baseband processor 34 can be configured to dynamically adjust the I signal and the Q signal and/or the I signal and the Q signal. The signal is associated with a power control signal to optimize the operation of the power amplifier system 26. For example, configuring the power amplifier system 26 in this manner can assist in controlling the power added efficiency (PAE) and/or linearity of the power amplifier 32. In some embodiments, the mixer 38, the ADC 39, and/or other suitable components may generally perform a quadrature (I/Q) demodulation function.

Although the power amplifier system 26 is illustrated as including a single power amplifier, the teachings herein are applicable to power amplifier systems that include multiple power amplifiers, including, for example, multi-mode and/or multi-mode power amplifier systems.

In addition, although FIG. 3 illustrates a specific configuration of a transceiver, other configurations are possible, including (for example) where the transceiver 13 includes more or fewer components and/or a group of different component configurations state.

As shown, the baseband processor 34 may include a digital predistortion (DPD) table 40, an equalizer table 41, and a complex impedance detector 44. The DPD table 40 can be stored in a non-volatile memory (for example, flash memory, read-only memory (ROM), etc.) of the transceiver 13 that can be accessed by the baseband processor 34. According to some embodiments, the baseband processor 34 accesses entries in the DPD table 40 to assist in the linearization of the power amplifier 17. For example, the baseband processor 34 selects an appropriate item in the DPD table 40 based on the sensed feedback signal 47, and adjusts the transmission signal accordingly before outputting the transmission signal to the I/Q modulator 37. For example, DPD can be used to compensate for certain non-linear effects of the power amplifier 17, including, for example, signal constellation distortion and/or signal spectrum spreading. According to certain embodiments including the illustrated embodiments, the DPD table 40 implements memoryless DPD, for example, where the current output of the DPD-corrected transmission signal depends only on the current input.

Overview of equalization using a lookup table with one of the values obtained by the pre-characterized RF front-end

Certain factors can contribute to the memory effect that is difficult to handle using pure memoryless DPD through the DPD table 40, such as the inherent group delay in the duplexer of the RF front-end 12 and the power amplifier 17 Poor impedance matching experienced. To compensate for these memory effects and/or other factors that contribute to non-linearity or other signal degradation, the power amplifier system 26 may employ an equalizer table 41. The equalizer table 41 can be stored in a non-volatile memory (eg, flash memory, read-only memory (ROM), etc.). Depending on the embodiment, the non-volatile memory can be stored in the DPD table 40 The same memory in it, or a different memory. Although the DPD table 40 and the equalizer table 41 are shown as resident in the baseband processor 34 for the purpose of illustration, the memory device containing these tables may be resident on any suitable transceiver 13 Location or elsewhere in the wireless device 11.

The equalizer table 41 is populated during a characterization phase, which can be implemented at manufacturing, for example, where the power amplifier system 26 is characterized under selected input conditions. During characterization, the power amplifier system 26 may be characterized at selected complex impedance points, where certain variables are recorded at each complex impedance point. For example, a programmable antenna tuner can be connected to the power amplifier system 26 during characterization to set the desired complex impedance point. The system can additionally be characterized across other appropriate parameters. As an example, in some embodiments, the variables are additionally recorded across different channels and frequency bands, which may allow the power amplifier system 26 (e.g., DPD meter 40) to be applied to the duplexer ripple across a transmission channel, taking into account certain These memory effects, and other benefits. A bidirectional coupler or other suitable component can be used to capture the behavior of the power amplifier system 26 at each set point (e.g., each characterized combination of phase, VSWR, channel, and frequency band). Each of the recorded variables can be stored in the table along with the corresponding characterization set point value.

The recorded variables that form the characteristic information about each set point may include some or all of the following: (1) Between the RF signal delivered to the power amplifier 17 and the supply shaping signal through the supply control branch 48 A desired (e.g., optimal) relative delay of the power amplifier 17; (2) a compression level of the power amplifier 17, which can correspond to a compression level of the power amplifier 17 during peak envelope power operation; and (3) a maximum envelope power. 6A to 6B provide a portion of a table containing recorded variables that characterize an embodiment of a power amplifier system Examples of 600 and 650. For example, these tables may form or be used to generate part of the equalizer table 41. The characterization procedure will be described in further detail herein, for example, with respect to FIGS. 4A, 4B, 5, and 6A to 6B.

During operation, the impedance detector 44 is used to detect complex impedance (for example, VSWR and/or phase). The impedance detector 44 can be implemented in any suitable manner, and can include digital or analog circuits. For example, some or all of the impedance detector 44 may be implemented in the baseband processor 34, as shown. In some embodiments, some or all of the impedance detector resides in the feedback path outside the baseband processor 34. Some examples of compatible components for detecting complex impedance are provided in US Patent No. 8,723,531 entitled "Integrated VSWR Detector for Monolithic Microwave Integrated Circuits" (which is incorporated herein by reference). Herein, an embodiment of a procedure for determining complex impedance is shown and explained with reference to FIG. 9.

As shown, the equalizer table 41 may include one or both of a transmission table 42 and a supply control table 43. The transmission table 42 can be used to compensate the DPD table 40 to account for mismatches, non-linearities, etc., and the supply control table 43 can be used to control the delay of one of the delay components 33 of the supply control branch 48, for example, based on the RF transmission signal 49 and the supply shaping The desired relative delay between signals.

As indicated by the dashed line extending from the transmission table 42 to the transmission signal 49, instead of the compensation DPD table 40 or in addition to the compensation DPD table 40, the transmission table 42 can also be used to directly compensate the transmission signal 49. For example, in some cases, the power amplifier system 26 may be in a mode in which the DPD is turned off, and the transmission table 42 is used to compensate the transmission signal 49. As an example, before reaching a certain transmission power level (for example, 100 milliwatts) (when envelope tracking is turned on and DPD becomes more energy inefficient), DPD and envelope tracking are disabled. Furthermore, in some cases, only one of the transmission table 42 and the supply control table 43 is utilized at any given time. For example, in some embodiments, the supply control table 43 is used only when the power amplifier system 26 is in an envelope tracking mode, and when the power amplifier system 26 is not in the envelope tracking mode (for example, when in the APT Or in the fixed supply mode), the transmission table 42 is used. In some In the embodiment, the equalizer table 41 includes only one of the transmission table 42 and the supply control table 43. In addition, the information contained in the equalizer table 41 can be organized in various ways. For example, when shown as separate tables, the transmission table 42 and the supply control table 43 can be combined into a single table, or, in some embodiments, the information provided in the equalizer table 41 is combined with the DPD table 40 Together.

For broadband signals such as 50 resource block (RB) LTE signals, the memory effect can become a particularly significant problem due to the load line and delay variation across the RB frequency span. Under a VSWR of 2:1 or greater, a memoryless DPD table 40 may not be sufficient to resolve AM-AM/AM-PM response changes across channels. In these situations, the equalization of the baseband transmission signal (for example, I/Q signal) may be appropriate, for example, using an equalizer table 41, which can enhance the DPD table 40 with memory coefficients. The use of the equalizer table 41 can implement an equalizer function that equalizes the compression level of the power amplifier 17 and/or achieves the desired (eg, optimal) delay of the power amplifier 17 across the frequency band. Therefore, the equalizer table 41, which can include the variables described above for cross-channel extraction, can be used to perform an equalizer function on a large RB signal (for example, 50 or 100 RB or uplink CA 40 MHz wide). According to some embodiments, equalization can provide a dual effect: adding memory effect compensation to the memoryless DPD and adapting the DPD to work under various characterization conditions (eg, characterization VSWR conditions). As explained, the equalizer function can have two paths, one for RF transmission signal 49 (for example, through the use of transmission table 42), and one for (for example) supply control that can be an envelope tracker Path 48 (for example, through the use of supply control table 43).

According to some implementations, the equalization table 41 includes individual gains and delays for each individual RB that are only applicable to the RF transmission signal 49, and there is no individual equalization of the supply control path 48. In another embodiment, the equalization table 41 implements a function close to a truncated Volterra series via the following two separate paths: one path is used for the RF transmission signal 49 and one path is used for Envelope tracker path 48. This implementation can be composed of a finite impulse response (FIR) filter, the finite impulse response (FIR) filter The wave device is followed by a non-linear look-up table, which is followed by another FIR. One block is applied to the RF signal and the other block is applied to the modulator signal. The self-equalization table and the nominal state memoryless DPD table derive FIR coefficients and non-linear look-up tables.

Exemplary Front End Module

4A and 4B show exemplary front-end modules 45, each of which is compatible with the system shown in FIGS. 1 to 3 and can be incorporated therein. 4A and 4B, the illustrated front-end module 45 includes an input switch 55, a set of power amplifiers 17, a set of duplexers 50, an antenna switch module 51, a two-way coupler 52 and a quantity测开关53。 Test switch 53. The front-end module 45 shown in FIG. 4B also includes an integrated antenna tuner 54.

The input switch 55 switches the modulated RF transmission signal between different power amplifiers 17 and corresponding duplexers 50. The power amplifier 17 is turned on to amplify the received signal and forward the amplified signal to the duplexer 50. The duplexer 50 is configured to forward the transmitted signal to the antenna switch module 51. For brevity, only the transmission path is shown in FIGS. 4A to 4B. However, it will be understood that the duplexer 50 is configured to allow two-way communication between the transceiver 13 and the antenna 14. For example, the duplexer 50 may be additionally configured to receive the received signal from one of the antenna switch modules 51 and forward the received signal for delivery to the transceiver 13. The duplexer 50 may additionally implement filtering or other appropriate functionality. For example, the duplexer 50 can provide rejection of transmitter noise at the receiving frequency, isolation to prevent reception desensitization, and so on.

The antenna switch module 51 can be configured to electrically connect the antenna 14 to a selected transmission or connection path. Therefore, the antenna switch module 51 can provide many switching functions associated with the operation of the front-end module 45. In some embodiments, the antenna switch module 51 may include a large number of switches that are configured to provide, for example, switching between different frequency bands, switching between different power modes, transmission mode, and reception. The functionality associated with switching between modes or a certain combination. The antenna switch module 51 can also be configured to provide additional functionality, including signal filtering and/or duplexing.

The illustrated embodiment includes the ability to provide a sensed output signal to the measurement switch Off 53 is a two-way coupler 52. For example, the measurement switch 53 can be a single pole double throw (SPDT) switch. According to certain embodiments including the illustrated embodiments, the directional coupler can provide a measure of both incident and reflected signals (e.g., forward power and reverse power) in the transmission path. For example, the bidirectional coupler 52 may have at least four ports. The four ports may include an input port configured to receive the signal generated by the power amplifier 17, an output port coupled to the antenna 14, and a configured To provide forward power to a first measurement port of the measurement switch 53 and configured to provide reverse power to a second measurement port of the measurement switch 53. Although the illustrated embodiment includes a bidirectional coupler 52, other types of devices or combinations of devices may be used in some embodiments. Generally speaking, any device capable of detecting both incident and reflected signals (for example, forward power and reverse power) in the transmission path can be used. The bidirectional coupler 52 outputs the transmission signal for delivery to the antenna and outputs the forward power signal and the reverse power signal to the measurement switch 53. The measurement switch 53 switches between the two ports (for example, between the detected forward power signal and the reverse power signal), and forwards the switched output for delivery to the impedance detector.

Compared with the front-end module 45 shown in FIG. 4B, the front-end module 45 shown in FIG. 4A does not include a programmable antenna tuner. In this embodiment, the equalizer table 41 can be used to accurately compensate for memory effects such as their memory effects due to mismatches without using an integrated antenna tuner, thereby reducing cost and complexity. And also avoid the loss caused by incorporating an antenna tuner. In these situations, a programmable antenna tuner can be temporarily connected to the system, for example, between the bidirectional coupler 52 and the antenna to characterize the system. For example, the antenna tuner can be used to set the complex impedance value for each characterization set point during manufacturing. The configuration shown in FIG. 4A can be used in conjunction with the pre-characterized equalizer table 41 to achieve a linear improvement of at least 6 dB according to some embodiments.

In some other embodiments (such as the embodiment shown in FIG. 4B ), an integrated antenna tuner 54 is provided in the front-end module 45. The antenna tuner 54 includes a circuit in some embodiments, and the circuit includes a pi network and/or a T network. Antenna tuner 54 series can be programmed To provide impedance tuning and in some embodiments combined with the equalizer table 41 to compensate for the memory effect. For example, the programmable antenna tuner 54 can be used to provide a rough correction for certain non-linearities (for example, AM-AM and/or AM-PM response changes, memory effects, etc.). The antenna tuner 54 can be adjusted to provide an impedance tuning function so that the power amplifier 17 experiences a specific impedance close to a desired value (for example, 50 ohms), thereby providing VSWR compensation. On the other hand, the equalizer table 41 can be used to provide fine corrections for certain non-linearities (for example, AM-AM and/or AM-PM response changes, memory effects, etc.). The inclusion of an integrated antenna tuner 54 can provide an additional benefit of providing calibration for the bidirectional coupler 52. For example, the directivity of the coupler 52 may be software or firmware enhanced by de-embedding, linear transformation, etc. after calibration. The integrated tuner 54 can also provide improved performance under server mismatch conditions.

The characterization of the front-end module 45 can be performed at any desired frequency, including on a part-by-part basis, or on a part-by-part basis or part-by-part basis in order to reduce calibration costs.

Examples of methods used to pre-characterize front-end modules

FIG. 5 shows a flowchart 500 of a process used to pre-characterize a front-end module. The procedure 500 can result in one measurement of the AM-AM and/or AM-PM response curve for each individual characterization state. One or more processors and/or other suitable components of a wireless device may implement certain parts of the program. For example, although some parts of the program are described as being implemented as certain components of the device shown in FIGS. 3 and 4A to 4B for the purpose of illustration, the program can use the wireless device 11 of FIG. 1 or Any other compatible wireless device 11 is implemented.

At block 502, the process includes: using a programmable antenna tuner to set the VSWR to an appropriate value for the current feature set point state. For example, referring to the first column 602 shown in the example partial equalizer look-up table 600 shown in FIG. 6A, the antenna tuner can be used to set the VSWR to a value corresponding to the current characterization set point state (1.2 ). In the case that an integrated antenna tuner 54 (FIG. 4B) is provided in the front-end module 45, the integrated tuning The tuner 54 can be used to adjust VSWR. For characterization purposes, an antenna tuner can be temporarily attached to the front-end module 45 without providing an integrated tuner (FIG. 4A ). The antenna tuner can be adjusted when the integrated impedance detector 44 or other detectors are used to monitor the VSWR point until the set point is reached.

At block 504, other parameters corresponding to the current characterization set point are set to appropriate values. For example, referring again to the exemplary setting points corresponding to the first column 602 in the partial lookup table 600 shown in FIG. 6A, the phase, frequency channel and frequency band of the complex impedance can be set to appropriate values (0 degrees, 20525, B5 ). Some or all of these set points can be achieved by using a signal generator or other suitable tools to adjust a test input signal.

At block 506, the system is characterized with the current characterization state. For example, at 506, a set of variables associated with the behavior of the front-end module 45 is recorded. These variables can generally include any suitable variables or measured values that can be used to compensate for the non-linearity of the front-end module 45. For example, referring again to the first column 602 of the partial table 600 shown in FIG. 6A, the variables in the exemplary embodiment include (1) the RF signal delivered to the power amplifier 17 and the supply shaping through the supply control branch 48 A measured (for example, the best) relative delay between signals (1.11 nanoseconds [ns]); (2) A compression level (2.0dB) of the power amplifier 17, which can correspond to the compression power amplifier 17 at A degree of operation during peak envelope power; and (3) a maximum envelope power (29 decibels milliwatt [dBm]). Referring to FIG. 6B (which includes another example of a part of the lookup table 650), the recorded variables may also include: AM-AM coefficients (Var B) and AM-PM coefficients (Var C).

At block 508, the variables are recorded in the lookup table 41 or otherwise stored in the non-volatile memory. In some embodiments, the variables are directly recorded in a non-volatile memory in the transceiver 13 during characterization (for example, to form an equalizer table 41). In other cases, the variables are recorded to some separate storage medium (for example, a fast drive, disk drive, or the like), and downloaded to the baseband processor in the wireless device 11 at a later point in time 34 or other suitable locations. For example, in some cases, the front-end module The group 12 is characterized before the wireless device 11 is assembled, and the recorded value is downloaded to a non-volatile memory accessible by the baseband processor 34 or one of the wireless devices 11 when the wireless device 11 or part of it is assembled In other suitable locations.

The procedure is then repeated for the next characterization set point. Referring again to FIG. 6A, the next set point may correspond to the second column 604 in the partial table 600, where the phase value is set to 45 degrees.

Figure 6A shows only part of the characterization table, where the phase is scanned as the value increases while keeping the other set point parameters (VSWR, channel and frequency band) constant. It will be understood that in order to complete the characterization and thereby obtain a complete set of recorded values for use in the equalization table 41, the phase can be scanned through additional values (e.g., through 360 degrees), and each of the other set point parameters It can also be scanned while keeping some or all of the other parameters constant.

Although the partial tables 600 and 650 shown in FIGS. 6A to 6B are referred to herein as forming part of the equalizer table 41, the values in the partial tables 600 and 650 are not substantially directly stored in some cases. Equalizer table 41. Alternatively, the recorded values from the tables 600, 650 are used to derive the values contained in the equalizer table 41. For example, the AM-AM coefficient (Var B) and AM-PM coefficient (Var C) shown in the partial table 650 of FIG. 6B can be derived from other variables recorded during the characterization.

According to some embodiments, some or all of the characterization process 500 is executed when DPD is disabled.

Figures 7A and 7B show an example procedure for compensating the operation of the front-end module using an equalizer table having a value obtained during the characterization of one of the front-end modules. For example, the procedure may involve the use of the equalizer table 41 shown in FIG. 3, and the equalizer table may be obtained using the procedure shown in FIG. 5 or a similar procedure. Although some parts of the program are described as being implemented by the baseband processor 34 in the transceiver 13 of the power amplifier system 26 of FIG. 3 for illustrative purposes, the program may be implemented by any other suitable processor, such as It is implemented by another processor in the transceiver 13 of the power amplifier system 26 in FIG. 3, by a processor in the wireless device 11 in FIG. 2, etc.).

Referring to FIG. 7A, at block 702, the baseband processor 34 receives a complex impedance value (for example, VSWR and/or phase) sensed by the impedance detector 44 during signal transmission.

At block 704, the baseband processor 34 uses the sensed impedance value to access the appropriate record from the equalizer table 41. For example, referring to the partial tables 600, 650 shown in FIGS. 6A to 6B, the VSWR can index the equalizer table 41 along with other characterization set point parameters (eg, phase, channel, and frequency band information). The phase, channel, and frequency band information can be known by the baseband processor 34 based on the current operating settings of the wireless device 11, or in some cases one or more of the phase, channel, and frequency band can be derived from the sensed feedback signal.

At block 706, the baseband processor 34 applies a correction based on the accessed record. Depending on the embodiment, the accessed record from the equalization table 41 may include the value of one or more of the variables recorded during the characterization (eg, RF vs. envelope tracker delay, compression level, and Pmax). In such situations, the baseband processor 34 may process the variables to apply appropriate corrections. As an example, to track the power amplifier compression, the baseband processor 34 can adjust the input signal to achieve the desired compression level. For example, if a compression level of 2.0 dBm is specified in the accessed record, the current gain is determined to be 2.7 dBm, and the baseband processor 34 can reduce the input signal level accordingly. Regarding the delay offset, the baseband processor 34 can set the programmable delay of the delay element 33 according to the delay offset specified in the accessed record.

Indexed records may contain values derived from independent variables in some cases. For example, in the case of recording for compensating the DPD table, the correction value can be derived from the recorded variable and stored in the equalizer table 41.

Figure 7B shows another procedure 750 that uses a pre-characterized look-up table to compensate for front-end module operation. Similar to the procedure 700 of FIG. 7A, at block 752, the baseband processor 34 receives the sensed complex impedance value.

At block 754, an antenna tuner 54 integrated in the front-end module 45 is used to perform a coarse tuning function. As previously explained in relation to FIG. 4B, the programmable antenna tuner 54 can be tuned to compensate to a certain extent for the sensed mismatch, for example by a power amplifier The impedance load experienced by 17 is tuned to be close to a desired value (for example, close to 50 ohms), thereby reducing VSWR.

At block 756, the baseband processor 34 uses the sensed impedance value to access the appropriate record from the equalizer table 41, similar to the block diagram 704 of the procedure 700 of FIG. 7A. At block 758, baseband processor 34 applies a fine tuning correction based on the accessed records in a manner similar to block 706 of procedure 700 of FIG. 7B. For example, fine tuning can compensate for non-linearities (eg, memory effects) that are relatively smaller than the magnitude of the non-linearities that can be accounted for by the coarse correction achieved by using the antenna tuner 54.

Examples of power amplifier application modes

8A to 8C show the waveforms of power amplifiers operating in a fixed supply voltage mode, an average power tracking (APT) mode, and an envelope tracking mode, respectively.

In FIG. 8A, a graph 800 illustrates the voltage of an RF signal 804 and a power amplifier supply voltage 802 versus time. The RF signal 804 has a signal envelope 805. It may be important that the power amplifier supply voltage 802 of the power amplifier has a voltage level greater than the voltage level of the RF signal 804. For example, providing a supply voltage having a magnitude less than the magnitude of the RF signal 804 to a power amplifier can cut the signal, thereby causing signal distortion and/or other problems. Therefore, it may be important that the power amplifier supply voltage 802 is greater than the voltage of the signal envelope 805. However, it can be expected to reduce a voltage difference between the power amplifier supply voltage 802 and the signal envelope 805 of the RF signal 804. This is because the area between the power amplifier supply voltage 802 and the signal envelope 805 can represent a loss of energy, which can reduce Battery life and increase the heat generated in a mobile device.

FIG. 8B is a graph 806 illustrating the change or change of a power amplifier supply voltage 808 with respect to the signal envelope 807 of the RF signal 810. The graph shown in FIG. 8B may correspond to an average power tracking (APT) mode of power amplifier operation. Compared with the power amplifier supply voltage 802 of FIG. 8A, the power amplifier supply voltage 808 of FIG. 4B causes the discrete voltage increments to change during different time slots (shown by dashed lines). For example, at a specific time slot The amplifier supply voltage 808 during the period can be adjusted based on the average power of the envelope 807 during that time slot. For example, the time slot on the right side may correspond to a lower operating power mode than the time slot on the left side. By reducing the supply voltage during a specific time slot, the APT operation can improve power efficiency compared to the fixed supply operation shown in FIG. 8A.

In FIG. 8C, a graph 812 illustrates the voltage of an RF signal 816 and a power amplifier supply voltage 814 versus time. The graph shown in FIG. 8C may correspond to an envelope tracking mode of the power amplifier operation. Compared with the power amplifier supply voltage 802 of FIG. 8A, the power amplifier supply voltage 814 of FIG. 8B changes or changes with respect to the signal envelope 815. The area between the power amplifier supply voltage 814 and the signal envelope 815 in FIG. 8C is smaller than the area between the power amplifier supply voltage 802 and the signal envelope 805 in FIG. The power amplifier system is associated. By tracking the supply voltage to the envelope, the envelope tracking operation can improve power efficiency as compared with both the fixed supply operation shown in FIG. 8A and the APT mode shown in FIG. 8B.

Although FIGS. 8A to 8C illustrate three examples of power amplifier supply voltage versus time, the teachings in this article are applicable to other configurations of power supply generation. For example, the teaching in this article is applicable to a configuration in which a supply voltage module limits a minimum voltage level of the power amplifier supply voltage.

Example method to determine complex impedance

FIG. 9 shows a flowchart of an exemplary method 900 for determining complex impedance. For example, the determined impedance can be used to access records in the equalizer table 41 and/or during the characterization process.

At block 902, the method 900 includes sampling the incident transmission signal path, for example, the measurement switch 53 is switched to receive the forward power signal from the corresponding port of the bidirectional coupler 52. At block 904, the method includes obtaining ideal I/Q data from the baseband processor 34. For example, the I/Q data can correspond to the data stream before the transmitted data stream is affected by the mismatch in the front-end module 45 and other effects. At block 906, the baseband processor 34 or its Other appropriate components make the ideal I/Q data cross-correlated and time aligned with the I/Q data received from the front-end module 45 for the incident path. For example, the baseband processor 34 may use a sub-sample shift technique. At block 908, the baseband processor 34 or other appropriate component calculates a complex phasor associated with the incident signal, which can be calculated according to the exemplary equation shown in block 908 of FIG. 9.

At block 910, the power amplifier system 26 switches the measurement switch 53 so that the switch is coupled to the reverse power signal from the corresponding port of the bidirectional coupler 52. At block 912, the reflected transmission signal path is sampled. At block 914, the method includes: obtaining ideal I/Q data from the baseband processor 34. The ideal I/Q data may correspond to the data stream before the transmission is affected by the mismatch in the front-end module 45 and other effects. The data stream. At block 916, the baseband processor 34 or other suitable components cross-correlate and time-align the ideal I/Q data with the I/Q data received from the front-end module 45 for the incident path. For example, the baseband processor 34 may use a sub-sample shift technique. At block 918, the baseband processor 34 or other appropriate component calculates a complex phasor associated with the incident signal, which can be calculated according to the exemplary equation shown in block 918 of FIG. 9.

At block 920, the baseband processor 34, impedance detector 44, or other appropriate component calculates the original gamma (eg, complex impedance). For example, the original gamma is calculated by dividing the calculated amount of reflected complex phase by the incident complex phase.

application

Some of the above-explained embodiments have provided examples in conjunction with mobile phones. However, the principles and advantages of these embodiments can be applied to any other systems or devices that require a power amplifier system.

These power amplifier systems can be implemented in various electronic devices. Examples of such electronic devices may include, but are not limited to, consumer electronic products, components of consumer electronic products, electronic test equipment, and the like. Examples of such electronic devices may also include, but are not limited to, circuits of memory chips, memory modules, optical networks or other communication networks, and disk drive circuits. Consumer Electronic products may include, but are not limited to, a mobile phone, a telephone, a television, a computer monitor, a computer, a handheld computer, a digital assistant (PDA), a microwave oven, a refrigerator, a car, and a stereo System, a card recorder or player, a DVD player, a CD player, a VCR, an MP3 player, a radio, a camcorder, a camera, a digital camera, a portable memory Body chip, a washing machine, a drying machine, a washing machine/drying machine, a photocopier, a fax machine, a scanner, a multi-function peripheral device, a watch, a clock, etc. In addition, these electronic devices may include non-finished products.

in conclusion

Unless the content context clearly requires otherwise, the description and the scope of the patent application are described throughout , The terms "comprise", "comprising" and the like should be interpreted as in the inclusive sense opposite to an exclusive or exhaustive sense; that is, in the sense of "including but not limited to" on. As commonly used herein, the term "coupled" refers to two or more elements that can be directly connected or connected by means of one or more intermediate elements. Likewise, as commonly used herein, the term "connected" refers to two or more elements that can be connected directly or by means of one or more intermediate elements. In addition, when used in this application, the wording "herein", "above", "below" and words of similar meaning should treat this application as a whole rather than any specific part of this application. Where the content context permits, the words using the singular or plural number in the above embodiments may also include the plural or singular number, respectively. Refer to the wording "or" in a list containing two or more items. That wording covers all of the following interpretations of the wording: any one of the items in the list, all the items in the list And any combination of items in the list.

In addition, unless otherwise specified or otherwise understood as used in the context of the content, the conditional language used in this article (such as "can", "could", "may", "可 (may)" (can)", "for example", "for example", "such as (such as)” and others) are generally intended to convey that certain embodiments include certain features, elements, and/or states while other embodiments do not. Therefore, this conditional language is generally not intended to imply that one or more embodiments require features, elements, and/or states in any way or that one or more embodiments are necessarily included in any decision with or without author input or prompting. Does a particular embodiment include or execute the logic of these features, elements, and/or states.

The above detailed description of the embodiments of the present invention is not intended to be exhaustive or to limit the present invention to the precise form disclosed above. Although the specific embodiments and examples of the present invention are described above for the purpose of explanation, those skilled in the art will recognize that various equivalent modifications can be made within the scope of the present invention. For example, although the procedures and blocks are presented in a predetermined order, alternative embodiments can also execute routines with steps in a different order, or use a system with blocks, and can delete, move, add, and subdivide. , Combine and/or modify certain programs or blocks. Each of these procedures or blocks can be implemented in a variety of different ways. Likewise, although procedures or blocks are sometimes shown as being executed continuously, these procedures or blocks may alternatively be executed in parallel, or may be executed at different times.

The teachings of the present invention provided herein can be applied to other systems, not necessarily the systems described above. The elements and actions of the various embodiments described above can be combined to provide further embodiments.

Although certain embodiments of the present invention have been described, these embodiments are presented only by way of example and are not intended to limit the scope of the present invention. In fact, the novel methods and systems described herein can be embodied in various other forms; in addition, various omissions, substitutions and changes can be made to the forms of the methods and systems described herein without departing from the spirit of the present invention. The scope of the attached patent application and its equivalent scope are intended to cover these forms or modifications that will belong to the scope and spirit of the present invention.

12‧‧‧RF Front End/Front End Module

13‧‧‧Transceiver

14‧‧‧antenna

17‧‧‧Power Amplifier

26‧‧‧Power Amplifier System

30‧‧‧Supply control driver

33‧‧‧Delay component

34‧‧‧Baseband processor

35‧‧‧Supply forming blocks or circuits

36‧‧‧Digital to Analog Converter

37‧‧‧Quadrature (I/Q) Modulator

38‧‧‧Mixer

39‧‧‧Analog to Digital Converter

40‧‧‧Digital Predistortion Meter

41‧‧‧Equalizer Table/Lookup Table/Equalizer Table

42‧‧‧Transmission Table

43‧‧‧Supply Control Table

44‧‧‧Complex Impedance Detector/Impedance Detector

45‧‧‧Front-end module

47‧‧‧Feedback signal

48‧‧‧Supply shaping branch/supply control path/envelope tracker path/supply control branch

49‧‧‧RF transmission signal

Vcc_pa‧‧‧Power amplifier supply voltage

Claims (20)

A power amplifier system includes: a modulator configured to generate a radio frequency transmission signal; a front-end module including a power configured to amplify the radio frequency transmission signal to generate an amplified radio frequency transmission signal An amplifier and a coupler positioned between an antenna and the power amplifier, the coupler configured to output one of the forward power and reverse power measurements associated with the amplified radio frequency transmission signal; one or more A non-volatile memory device that stores an equalizer table, the equalizer table having a plurality of characterization states corresponding to different input conditions and generated during a pre-characterization period of one of the front-end modules Items, the one or more non-volatile memory devices store a digital predistortion table, the digital predistortion table is configured to implement memoryless digital predistortion on the radio frequency transmission signal; and a processor, which It is configured to: (a) receive the measured voltage standing wave ratio derived from the forward power and the reverse power output from the coupler, (b) be based at least in part on the measured voltage standing wave ratio Access the items in the equalizer table, and (c) before amplifying the radio frequency transmission signal by the power amplifier, adjust the digital predistortion table and the accessed items from the equalizer table before The radio frequency transmits the signal to compensate for one or more memory effects existing in the power amplifier system. Such as the power amplifier system of claim 1, wherein the equalizer table is generated using a programmable antenna tuner, and the programmable antenna tuner is used to tune the front-end module to a desired voltage standing wave ratio point. Such as the power amplifier system of claim 1, wherein the front-end module does not include an integrated antenna tuner. The power amplifier system of claim 1, wherein the front-end module further includes a programmable antenna tuner positioned between the antenna and the coupler. The power amplifier system of claim 1, wherein the front-end module further includes one or more duplexers, and the one or more duplexers are positioned between the power amplifier and the bidirectional coupler and contribute to the memory effects At least some memory effects. The power amplifier system of claim 4, wherein the programmable antenna tuner can be adjusted to tune an impedance experienced by the power amplifier so as to provide a rough nonlinear correction in the power amplifier system, and based on the accessed The project's adjustment of the radio frequency transmission signal provides fine non-linear correction in the power amplifier system. Such as the power amplifier system of claim 1, wherein the coupler is a bidirectional coupler. Such as the power amplifier system of claim 1, wherein the processor is further configured to adjust the radio frequency transmission signal by adapting the values in the digital predistortion table based on the accessed items in the equalizer table. The power amplifier system of claim 1, further comprising an envelope tracking system configured to provide the power supply control signal to the power amplifier to control a voltage level of the power amplifier based on a shaped envelope signal Therefore, the processor is further configured to adjust a delay between the RF transmission signal and the supply control signal based on the delay value included in the accessed equalizer table entries. A mobile device includes: a modulator configured to generate a radio frequency transmission signal; a front-end module including a power amplifier configured to amplify the radio frequency transmission signal to generate an amplified radio frequency transmission signal And a coupler configured to receive the amplified radio frequency transmission signal, the power amplifier is configured to receive a power amplifier supply voltage for powering the power amplifier, the coupler is configured to output and the Amplify one of the measurement of the forward power and the reverse power associated with the radio frequency transmission signal; An antenna configured to transmit the amplified radio frequency transmission signal; one or more non-volatile memory devices, which store an equalizer table, the equalizer table has a plurality of corresponding to different input conditions For a plurality of items generated during a pre-characterization period of one of the front-end modules under the characterization state, the one or more non-volatile memory devices store a digital predistortion table, and the digital predistortion table is configured to Implement memoryless digital predistortion on the radio frequency transmission signal; and a processor configured to: (a) receive the forward power output from the coupler and the voltage standing wave ratio derived from the reverse power (B) access the items in the equalizer table based at least in part on the measured values of the voltage standing wave ratio, and (c) before amplifying the radio frequency transmission signal by the power amplifier, based on the digital The predistortion table and the accessed items adjust the radio frequency transmission signal to compensate for one or more memory effects existing in the power amplifier system. The mobile device of claim 10, wherein the front-end module further includes one or more duplexers that promote at least some of the one or more memory effects. Such as the mobile device of claim 10, wherein the equalizer table is generated using a programmable antenna tuner, and the programmable antenna tuner is used to tune the front-end module to a desired voltage standing wave ratio point. Such as the mobile device of claim 10, wherein the front-end module does not include an integrated antenna tuner. Such as the mobile device of claim 10, wherein the front-end module further includes a programmable antenna tuner positioned between the antenna and the coupler. A power amplifier system, comprising: a front-end module, which includes a power amplifier configured to amplify a radio frequency transmission signal to generate an amplified radio frequency transmission signal, a programmable antenna tuner coupled to an antenna, and positioning A coupler between the power amplifier and the programmable antenna tuner, the coupler is configured to output and the amplified radio frequency transmission The output signal is associated with one of the forward power and the reverse power measurement. The programmable antenna tuner can be adjusted to tune an impedance experienced by the power amplifier to provide a rough nonlinear correction in the power amplifier system; Or a plurality of non-volatile memory devices, which store an equalizer table, the equalizer table having a plurality of characterization states corresponding to different input conditions and during a pre-characterization period of the front-end module Generates a plurality of items, the one or more non-volatile memory devices store a digital predistortion table, the digital predistortion table is configured to implement digital predistortion on the radio frequency transmission signal; and a processor, It is configured to: (a) receive the measured value of the voltage standing wave ratio derived from the forward power and the reverse power output from the coupler, (b) access the equalization based at least in part on the voltage standing wave ratio And (c) adjust the radio frequency transmission signal based on the digital predistortion table and the accessed items before amplifying the radio frequency transmission signal by the power amplifier. Such as the power amplifier system of claim 15, wherein the front-end module further includes a duplexer. The power amplifier system of claim 15, wherein the duplexer is positioned between the power amplifier and the coupler. Such as the power amplifier system of claim 15, wherein the coupler is a bidirectional coupler. Such as the power amplifier system of claim 15, wherein the processor is further configured to adjust the radio frequency transmission signal by adapting the values in the digital predistortion table based on the accessed items in the equalizer table. The power amplifier system of claim 15, which further includes an envelope tracking system configured to provide the power supply control signal to the power amplifier to control one of the power amplifiers based on a shaped envelope signal and delay Voltage level.

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