Envelope tracking power supply modulator and related methods and systems

Abstract

The present invention provides an envelope tracking power modulator, which includes an amplifier circuit and a zero peak circuit. The amplifier circuit receives an envelope input, generates a modulated power supply voltage according to the envelope input, and provides the modulated power supply voltage to a power amplifier. The zero peak circuit is coupled to the amplifier circuit and applies a zero peak value to the amplifier circuit, wherein the zero peak value inserts a zero point at a frequency. Accordingly, the present invention also provides a wireless communication system and an envelope tracking calibration method, wherein the zero peak circuit inserts a zero point at a frequency to increase the bandwidth of envelope tracking without requiring additional static current consumption.

Description

Technical Field

[0001] The present invention relates to envelope tracking, and more particularly, to an envelope tracking power supply modulator with zero peaking and a related envelope tracking calibration method and system. Background Art

[0002] A power amplifier (PA) is used to amplify radio-frequency (RF) signals for radio transmission. PAs are common in wireless communication devices used to drive one or more antennas of a transmitter. The power consumption of the PA is critical for battery-powered wireless communication devices. Traditionally, the PA is biased by a fixed supply voltage. When the RF input signal input to the PA is at a maximum level, a peak RF output power condition usually occurs. However, when the PA exits from this peak RF output power condition, the excess input power must be dissipated by the PA because the excess input power is not converted into useful RF output power. That is, the traditional fixed PA supply voltage results in a large amount of power loss (such as heat). Envelope tracking is a technology that requires the power supply voltage of the PA to be dynamically modulated using the envelope of the RF input signal. This will keep the PA operating close to the peak level at all times and greatly improve the efficiency of the PA. That is, envelope tracking techniques modulate the PA supply voltage to track the envelope of the RF input signal to reduce the power dissipated as heat.

[0003] In wireless communications, bandwidth is the frequency range occupied by the modulated carrier signal. With the advancement of wireless communication technology, a modulated carrier signal uses wider and wider bandwidths. Therefore, envelope tracking power modulators (which are used to provide modulated power supply voltages to the PA) require wide bandwidth linear amplifiers. Typically, the transconductance (bias current) of the linear amplifier is increased to enhance bandwidth and linearity. Since linear amplifiers require large bias currents to push the dominant pole to higher frequencies, traditional wide bandwidth envelope tracking designs consume a lot of power. In addition, considering the use of mature processes (such as 18nm processes) to manufacture envelope tracking power modulators, the quiescent current of the linear amplifier increases dramatically for wide bandwidth envelope tracking.

[0004] Therefore, an innovative design is needed that can achieve wide bandwidth envelope tracking without increasing quiescent current consumption. Summary of the invention

[0005] In view of this, one of the objectives of the present invention is to provide an envelope tracking power modulator with zero peak value and a related wireless communication system and envelope tracking calibration method, which can increase the bandwidth of envelope tracking without additional static current consumption.

[0006] In a first aspect, the present invention provides an envelope tracking power modulator, comprising an amplifier circuit and a zero peak circuit. The amplifier circuit is arranged to receive an envelope input, generate a modulated power supply voltage according to the envelope input, and provide the modulated power supply voltage to a power amplifier. The zero peak circuit is coupled to the amplifier circuit and is used to apply a zero peak to the amplifier circuit, wherein the zero peak inserts a zero point at a frequency.

[0007] In some embodiments, the frequency of the zero inserted by the zero-peak is equal to the main pole frequency.

[0008] In some embodiments, the zero-peak circuit is adjustable, and the zero-peak circuit may include a frequency adjustment circuit for adjusting the frequency of the zero point inserted by the zero-peak circuit. For example, a plurality of zero-peak settings corresponding to a plurality of frequencies (such as frequencies corresponding to a plurality of poles, but not limited thereto, for example, a plurality of frequencies located near the main pole frequency) may be preset, and the best target zero-peak setting (such as selecting the zero-peak setting corresponding to the minimum ACLR) may be selected from the plurality of zero-peak settings by measuring the ACLR at each of the plurality of zero-peak settings.

[0009] In some embodiments, the zero-peak circuit is adjustable, and the zero-peak circuit includes a gain adjustment circuit for adjusting the gain introduced by the zero point inserted by the zero-peak circuit. For example, there are multiple zero-peak settings corresponding to multiple gains for the same zero-point frequency, and the best target zero-peak setting (such as selecting the zero-peak setting corresponding to the minimum ACLR) is selected from the multiple zero-peak settings by measuring ACLR at each setting in the multiple zero-peak settings.

[0010] In a second aspect, the present invention also provides a wireless communication system, comprising: a transmitting (TX) circuit, for receiving a TX baseband signal, generating a radio frequency (RF) signal according to the TX baseband signal, and outputting the RF signal via a power amplifier PA; an envelope tracking circuit, for obtaining an envelope input from the TX baseband signal, and generating a modulated power supply voltage according to the envelope input, wherein the envelope tracking circuit envelope tracks a power supply modulator, and the envelope tracking power supply modulator comprises an amplifier circuit and an adjustable zero peak circuit; the amplifier circuit is used to receive the envelope input, generate the modulated power supply voltage according to the envelope input, and provide the modulated power supply voltage to the PA; the adjustable zero peak circuit is coupled to the amplifier circuit and is used to apply a zero peak value to the amplifier circuit, wherein the zero peak value is inserted into a zero point at a frequency; a receiving (RX) circuit, for receiving the output of the PA, and obtaining an RX baseband signal from the output of the PA; and an envelope tracking calibration circuit, for calibrating the adjustable zero peak circuit by analyzing the RX baseband signal.

[0011] In some embodiments, the adjustable zero peak circuit includes: a frequency adjustment circuit for adjusting the frequency of the zero point inserted by the zero peak, wherein the frequency adjustment circuit operates under the control of the envelope tracking calibration circuit, for example, selecting an optimal target zero peak setting from a plurality of zero peak settings corresponding to a plurality of frequencies.

[0012] In some embodiments, the adjustable zero peak circuit includes: a gain adjustment circuit for adjusting the gain introduced by the zero point inserted by the zero peak, wherein the gain adjustment circuit operates under the control of the envelope tracking calibration circuit. For example, the best target zero peak setting is selected from multiple zero peak settings corresponding to multiple gains for the same frequency.

[0013] In some embodiments, the envelope tracking calibration circuit is used to calculate an adjacent channel leakage ratio (ACLR) according to the RX baseband signal, and adaptively calibrate the adjustable zero peak circuit according to the ACLR.

[0014] In some embodiments, the adjustable zero-peak circuit is arranged to support a plurality of predetermined zero-peak settings, and the envelope tracking calibration circuit references the ACLR to select one of the plurality of predetermined zero-peak settings as a target zero-peak setting for the adjustable zero-peak circuit.

[0015] In a third aspect, the present invention provides an envelope tracking calibration method, comprising: receiving a transmit (TX) baseband signal, generating a radio frequency (RF) signal based on the TX baseband signal, and outputting the RF signal via a power amplifier PA; obtaining an envelope input from the TX baseband signal; an amplifier circuit generating a modulated power supply voltage based on the envelope input; providing the modulated power supply voltage to the PA; applying a zero-peak value to the amplifier circuit, wherein the zero-peak value is inserted into a zero point at a frequency; receiving an output of the PA and obtaining a received RX baseband signal from the output of the PA; and calibrating the zero-peak value by analyzing the RX baseband signal.

[0016] In some embodiments, calibrating the zero-peak value includes: adjusting the frequency of the zero point inserted by the zero-peak value.

[0017] In some embodiments, calibrating the zero-peak value includes adjusting a gain introduced by the zero point inserted by the zero-peak value.

[0018] In some embodiments, calibrating the zero-peak value by analyzing the RX baseband signal includes: calculating an adjacent channel leakage ratio (ACLR) according to the RX baseband signal; and adaptively calibrating the zero-peak value according to the ACLR.

[0019] In some embodiments, adaptively calibrating the zero-peak value according to the ACLR includes: selecting one of a plurality of predetermined zero-peak settings as a target zero-peak setting for the zero-peak value according to the ACLR.

[0020] Those skilled in the art will no doubt understand these and other objects of the present invention after reading the following detailed description of the preferred embodiments shown in the accompanying drawings. The detailed description will be given in the following embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention may be more fully understood by reading the following detailed description and by referring to the examples given in the accompanying drawings.

[0022] Figure 1 FIG. 4 is a block diagram of an envelope tracking power modulator according to an embodiment of the present invention.

[0023] Figure 2 FIG. 4 is a circuit diagram of a portion of an envelope tracking power modulator with zero peak value according to an embodiment of the present invention.

[0024] Figure 3 FIG. 4 is a block diagram of a wireless communication system according to an embodiment of the present invention.

[0025] Figure 4 FIG. 4 is a schematic diagram showing frequency responses of an envelope tracking power modulator under different zero-peak settings according to an embodiment of the present invention.

[0026] In the following detailed description, for the purpose of illustration, many specific details are set forth so that those skilled in the art can more thoroughly understand the embodiments of the present invention. However, it is apparent that one or more embodiments may be implemented without these specific details, and different embodiments may be combined as needed, and should not be limited to the embodiments listed in the accompanying drawings. DETAILED DESCRIPTION

[0027] The following description is a preferred embodiment of the present invention, which is only used to illustrate the technical features of the present invention, and is not used to limit the scope of the present invention. Certain words are used throughout the specification and claims to refer to specific components. It should be understood by those skilled in the art that manufacturers may use different names to refer to the same components. Therefore, the present specification and claims do not use the difference in name as a way to distinguish components, but use the difference in function of the components as a basis for distinction. The terms "component", "system" and "device" used in the present invention can be entities related to computers, wherein the computer can be hardware, software, or a combination of hardware and software. The terms "including" and "comprising" mentioned in the following description and claims are open-ended terms, so they should be interpreted as "including, but not limited to...". In addition, the term "coupled" means an indirect or direct electrical connection. Therefore, if a device is described as coupled to another device, it means that the device can be directly electrically connected to the other device, or indirectly electrically connected to the other device through other devices or connection means.

[0028] Corresponding numbers and symbols in the various figures of the drawings generally refer to corresponding parts unless otherwise indicated. The drawings are drawn to clearly illustrate the relevant parts of the embodiments and are not necessarily drawn to scale.

[0029] The term "substantially" or "approximately" as used herein means that within an acceptable range, a person skilled in the art can solve the technical problem to be solved and basically achieve the technical effect to be achieved. For example, "approximately equal to" means that a certain error from "completely equal to" is acceptable to a person skilled in the art without affecting the correctness of the result.

[0030] Figure 1 1 is a block diagram of an envelope tracking supply modulator (ETSM) according to an embodiment of the present invention. The envelope tracking supply modulator 100 includes an amplifier circuit 102 and a zero peaking circuit 104. The amplifier circuit 102 is used to receive an envelope input S ENV, according to the envelope input S ENV Generates a modulated supply voltage V PA , and the modulated power supply voltage V PA Provided to the power amplifier (PA) 101. The zero peak circuit 104 is coupled to the amplifier circuit 102 and is configured to apply zero peaking to the amplifier circuit 102, wherein the zero peaking inserts an additional zero at a selected frequency, thereby pushing the dominant pole to a higher frequency or making the dominant pole frequency higher. For example, the amplifier circuit 102 without the zero peak has an original dominant pole frequency. The amplifier circuit 102 with the zero peak has a zero peak frequency (the zero peak frequency is located at or near the original dominant pole frequency, that is, the zero peak frequency is approximately equal to the dominant pole frequency) to compensate for the amplifier gain loss at the original dominant pole frequency. That is, in an embodiment of the present invention, the above-mentioned selected frequency is equal to or approximately equal to the dominant pole frequency of the amplifier circuit 102 / envelope tracking power supply modulator 100. In this way, the bandwidth of envelope tracking can be increased without additional quiescent current consumption. For example, the 3dB frequency may be higher than 100MHz. It can be understood that, assuming that the transfer function of the envelope tracking power modulator 100 without the zero-peak circuit 104 is H(s), the zero-peak circuit 104 is configured to add at least one additional zero to the transfer function H(s) / envelope tracking power modulator 100, wherein the frequency of the additional zero is equal to or substantially / approximately equal to the main pole frequency or other pole frequency of the envelope tracking power modulator 100. For example, the pole frequency of the envelope tracking power modulator 100 / transfer function H(s) can be predetermined, so that if it is desired to push the frequency of a particular pole (such as the main pole) to a higher frequency, the selected frequency can be set to be approximately equal to the frequency of the particular pole, and a zero can be inserted at the selected frequency by the zero-peak circuit 104, so that the frequency of the particular pole is pushed to a higher frequency.

[0031] In this embodiment, the zero-peak circuit 104 is adjustable and includes a frequency adjustment circuit 106 and a gain adjustment circuit 108. The frequency adjustment circuit 106 is used to adjust the frequency of the additional zeros inserted by the zero-peak. Therefore, depending on actual design considerations, the zero-peak frequency (or the frequency of the additional zeros inserted) can be moved from one frequency value to another frequency value, for example, so that the ACLR is small or below a threshold. The gain adjustment circuit 108 is used to adjust the gain introduced by the additional zeros inserted by the zero-peak. Therefore, depending on actual design considerations, the zero-peak gain can be changed from one gain value to another gain value.

[0032] It should be noted that Figure 1 The envelope tracking power modulator 100 shown in FIG. 1 is for illustrative purposes only and is not intended to limit the present invention. For example, the zero peak circuit 104 can be modified to omit the gain adjustment circuit 108. For another example, the zero peak circuit 104 can be modified to omit the frequency adjustment circuit 106. For another example, the zero peak circuit 104 can be modified to have a fixed zero peak setting, for example, the frequency of the additional zero corresponding to the fixed zero peak setting is approximately equal to the main pole frequency. That is, any envelope tracking power modulator with zero peaking falls within the scope of the present invention.

[0033] In an exemplary design, amplifier circuit 102 is implemented using a multi-stage amplifier, and zero-peak circuit 104 provides zero peaking adjustment at an input stage (ie, the first stage) of the multi-stage amplifier. Figure 2 1 is a circuit diagram of a portion of an envelope tracking power modulator with zero peak value according to an embodiment of the present invention. The input stage of the amplifier circuit 102 (which is a multi-stage amplifier) ​​includes a plurality of P-type metal oxide semiconductor (PMOS) transistors MP1, MP2, MP3 and MP4 and a plurality of N-type metal oxide semiconductor (NMOS) transistors MN1 and MN2. The source terminal of the PMOS transistor MP1 is coupled to the supply voltage VDD. The source terminals of the NMOS transistors MN1 and MN2 are coupled to the ground voltage GND. The envelope input S ENV Is the positive signal V IPand negative signal V IN The in-phase signal V IP is coupled to the gate terminal of the PMOS transistor MP4. IN Coupled to the gate terminal of the PMOS transistor MP3. In this embodiment, zero-peak adjustment is achieved by two variable resistors VR1 and VR2. By appropriately setting the variable resistors VR1 and VR2, the zero-peak frequency can be changed to push the main pole at the node A / B to a higher frequency.

[0034] Considering that the zero-peak circuit 104 is adjustable, the zero-peak circuit 104 is automatically calibrated to achieve an optimized zero-peak setting. The present invention also proposes an envelope tracking power modulator, which can be calibrated by using a continuous-time adaptive gain equalization technique.

[0035] Figure 3 3 is a block diagram of a wireless communication system according to an embodiment of the present invention. The wireless communication system 300 includes a transmit (TX) circuit 302, an envelope tracking circuit 304, a receive (RX) circuit 306, and an envelope tracking (ET) calibration circuit 308. The transmit (TX) circuit 302 is arranged to receive a TX baseband signal TX_BB, generate a radio frequency (RF) signal TX_RF according to the TX baseband signal TX_BB, and output the RF signal TX_RF to an antenna 301 via a power amplifier (PA) 320. For example, the TX baseband signal TX_BB is a digital signal, the RF signal TX_RF is an analog signal, and the transmit (TX) circuit 302 includes a digital pre-distortion (DPD) circuit (represented by “DPD”) 312, a digital-to-analog converter (DAC) 314, an upconverter 316, an analog filter 318, and a power amplifier (PA) 320.

[0036] The envelope tracking circuit 304 is arranged to derive an envelope input S from the baseband signal TX_BB. ENV , and according to the envelope input S ENV Generates a modulated power supply voltage V PA , which is used as the power supply voltage of the power amplifier (PA) 320. For example, the TX baseband signal TX_BB is a digital signal, and the envelope input S ENVis an analog signal, and the envelope tracking circuit 304 includes an envelope tracking digital baseband circuit (envelope tracking digital baseband circuit) (represented by "ET DBB") 322, a DAC 324, an analog filter 326, and an envelope tracking supply modulator (ETSM) 328. The envelope tracking digital baseband circuit 322 may include a timing alignment block, an envelope detection block, a lookup table, etc. The PA supply voltage (i.e., V PA ) and the PA input signal (i.e., TX_RF) is critical. The timing alignment module of the envelope tracking digital baseband circuit 322 may include a delay circuit that is used to time-align the output of the envelope tracking power modulator 328 with the RF input (i.e., TX_RF) of the power amplifier (PA) 320. The envelope detection module of the envelope tracking digital baseband circuit 322 performs an envelope magnitude calculation. For example, the envelope magnitude V IN is calculated as the unsigned polar magnitude of the in-phase signal and the quadrature signal. Appropriate shaping is required to bias the power amplifier (PA) 320 within the valid operating range and improve the linearization characteristics. The envelope shaping can be provided by the lookup table of the envelope tracking digital baseband circuit 322, which determines the envelope magnitude (i.e., V IN ) and the PA supply voltage (i.e., V PA ) between them.

[0037] As described above, the envelope tracking power modulator 328 may be composed of Figure 1The envelope tracking power modulator 100 shown is implemented, and the envelope tracking power modulator 328 is adjustable and can be automatically calibrated to achieve an optimal zero peak setting. When the wireless communication system 300 operates in the calibration mode, the TX baseband signal TX_BB is configured to have a predetermined envelope pattern, and the RX circuit 306 is configured to receive the output PA_OUT of the power amplifier (PA) 320 via the coupler 310, and obtain the RX baseband signal RX_BB from the output PA_OUT of the power amplifier (PA) 320. For example, the RX circuit 306 includes a downconverter 330, an analog filter 332 and an analog-to-digital converter (ADC) 334.

[0038] When the wireless communication system 300 operates in the calibration mode, the envelope tracking (ET) calibration circuit 308 is a digital circuit configured to calibrate an adjustable zero-peak circuit (e.g., zero-peak circuit 104) included in the envelope tracking power modulator 328 by analyzing the RX baseband signal RX_BB. In this embodiment, the envelope tracking power modulator 328 can be composed of Figure 1 The envelope tracking power modulator 100 shown is implemented. Therefore, the envelope tracking calibration circuit 308 generates a control signal S_CTRL to the envelope tracking power modulator 328 to control one or both of the frequency adjustment circuit 106 and the gain adjustment circuit 108. For example, the envelope tracking calibration circuit 308 calculates the adjacent channel leakage ratio (ACLR) according to the RX baseband signal RX_BB, and adaptively calibrates the adjustable zero peak circuit 104 according to the ACLR. According to the proposed continuous-time adaptive gain equalization technique, the best zero peak setting (for example, the zero peak setting corresponding to the smallest ACLR value among multiple predetermined zero peak settings is selected as the best zero peak setting) can be achieved by finding the best ACLR (where ACLR is usually a negative value, the more negative the better, that is, the smaller the ACLR value, the better) for an envelope tracking bandwidth greater than 100 MHz.

[0039] The frequency adjustment circuit 106 and the gain adjustment circuit 108 of the adjustable zero-peak circuit 104 can be configured to allow the adjustable zero-peak circuit 104 to support a plurality of pre-defined zero-peak settings, wherein each pre-defined zero-peak setting is defined by a zero-peak frequency and a zero-peak gain. In the case where the envelope tracking power modulator 328 is implemented by the envelope tracking power modulator 100, the envelope tracking calibration circuit 308 can refer to a quality metric (e.g., ACLR) to select one of the plurality of pre-defined zero-peak settings as the target zero-peak setting of the adjustable zero-peak circuit 104 (e.g., select the zero-peak setting corresponding to the minimum ACLR value as the target zero-peak setting). Figure 4 1 is a schematic diagram of the frequency response of the envelope tracking power modulator under different zero peak settings according to an embodiment of the present invention. Assume that the adjustable zero peak circuit 104 supports four predetermined zero peak settings S1, S2, S3 and S4, and the four predetermined zero peak settings provide different high frequency gain compensation. Figure 4 As shown, when the predetermined zero peak setting S1 is selected, the high frequency gain at 100 MHz is 15.81 dB; when the predetermined zero peak setting S2 is selected, the high frequency gain at 100 MHz is 13.4 dB. When the predetermined zero peak setting S3 is selected, the high frequency gain at 100 MHz is 12.89 dB; when the predetermined zero peak setting S4 is selected, the high frequency gain at 100 MHz is 11.21 dB. As an example and not a limitation, the envelope tracking calibration circuit 308 can select the most appropriate zero peak setting from a plurality of predetermined zero peak settings by performing a binary search based on the calculated ACLR, wherein the most appropriate zero peak setting is associated with the best ACLR for an envelope tracking bandwidth of not less than 100 MHz.

[0040] In some embodiments of the present invention, the envelope tracking power modulator 100 / 328 can be part of a power management integrated circuit (PMIC), and the power amplifier 101 / 320 can be an external amplifier driven by the PMIC. Therefore, the AC channel between the PMIC and the power amplifier 101 / 320 can be routed on a printed circuit board (PCB). The parasitic components of the AC channel (used to transmit the PA supply voltage) introduce peaks within the desired bandwidth (e.g., 100 MHz or 200 MHz). The AC channel on the PCB is appropriately designed to ensure that the amplitude of the peak introduced by the parasitic components (such as resistors, inductors, and capacitors, RLC) is limited to an acceptable level, or the peak introduced by the parasitic RLC is pushed to a higher frequency (e.g., 100 MHz or 200 MHz) outside the required bandwidth.

[0041] Although the present invention has been described by way of example and in terms of preferred embodiments, it should be understood that the present invention is not limited to the disclosed embodiments. Instead, it is intended to cover various modifications and similar structures (as will be apparent to those skilled in the art), for example, combinations or replacements of different features in different embodiments. Therefore, the scope of the appended claims should be given the broadest interpretation to cover all such modifications and similar structures.

Claims

1. An envelope tracking power modulator, characterized in that: include: an amplifier circuit for receiving an envelope input, generating a modulated supply voltage based on the envelope input, and providing the modulated supply voltage to a power amplifier; as well as, The zero-peak circuit is coupled to the amplifier circuit and is used to apply a zero-peak value to the amplifier circuit, wherein the zero-peak value inserts a zero point at a predetermined frequency, and the predetermined frequency is equal to a main pole frequency of the amplifier circuit.

2. The envelope tracking power modulator according to claim 1, characterized in that: The zero-peak circuit is adjustable, and the zero-peak circuit comprises: The frequency adjustment circuit is used for adjusting the frequency of the zero point inserted by the zero peak value.

3. The envelope tracking power modulator according to claim 2, characterized in that: The frequency adjustment circuit includes a variable resistor coupled to an output node of an input stage of the amplifier circuit.

4. The envelope tracking power modulator according to claim 1, characterized in that: The zero-peak circuit is adjustable, and the zero-peak circuit comprises: The gain adjustment circuit is used for adjusting the gain introduced by the zero point inserted by the zero-peak value.

5. A wireless communication system, characterized in that: include: A TX transmission circuit is used to receive a TX baseband signal, generate a radio frequency RF signal according to the TX baseband signal, and output the RF signal via a power amplifier PA; An envelope tracking circuit, used for obtaining an envelope input from the TX baseband signal and generating a modulated power supply voltage according to the envelope input, wherein the envelope tracking circuit envelope tracks a power supply modulator, and the envelope tracking power supply modulator includes an amplifier circuit and an adjustable zero peak circuit; The amplifier circuit is used to receive the envelope input, generate the modulated power supply voltage according to the envelope input, and provide the modulated power supply voltage to the PA; The adjustable zero-peak circuit is coupled to the amplifier circuit and is used to apply a zero-peak to the amplifier circuit according to a plurality of predetermined zero-peak settings, wherein the zero-peak inserts a zero at a frequency; a receiving RX circuit, configured to receive the output of the PA and obtain an RX baseband signal from the output of the PA; and An envelope tracking calibration circuit is used to calculate a quality metric based on the RX baseband signal to calibrate the adjustable zero-peak circuit, wherein the envelope tracking calibration circuit selects one of the plurality of predetermined zero-peak settings as a target zero-peak setting of the adjustable zero-peak circuit with reference to the quality metric, so that the adjustable zero-peak circuit inserts the zero point according to the target zero-peak setting.

6. The wireless communication system according to claim 5, characterized in that: The adjustable zero peak circuit includes: A frequency adjustment circuit is used to adjust the frequency of the zero point inserted by the zero peak value, wherein the frequency adjustment circuit operates under the control of the envelope tracking calibration circuit.

7. The wireless communication system according to claim 5, characterized in that: The adjustable zero peak circuit includes: A gain adjustment circuit is used for adjusting the gain introduced by the zero point of the zero-peak insertion, wherein the gain adjustment circuit operates under the control of the envelope tracking calibration circuit.

8. The wireless communication system according to claim 5, characterized in that: The quality metric includes an adjacent channel leakage ratio (ACLR), and the envelope tracking calibration circuit is used to calculate the ACLR according to the RX baseband signal and adaptively calibrate the adjustable zero peak circuit according to the ACLR.

9. The wireless communication system according to claim 6, characterized in that: The frequency adjustment circuit includes a variable resistor coupled to an output node of an input stage of the amplifier circuit.

10. An envelope tracking calibration method, characterized in that: include: Receive the transmitted TX baseband signal, generate a radio frequency RF signal according to the TX baseband signal, and output the RF signal through a power amplifier PA; Obtaining an envelope input from the TX baseband signal; The amplifier circuit generates a modulated supply voltage in response to the envelope input; providing the modulated power supply voltage to the PA; applying a zero peak to the amplifier circuit according to a plurality of predetermined zero peak settings, wherein the zero peak inserts a zero at a frequency; receiving an output of the PA and obtaining a receive RX baseband signal from the output of the PA; and, Calculating a quality metric based on the RX baseband signal to calibrate the zero peak value; Wherein, calibrating the zero peak value includes: One of the plurality of predetermined zero-peak settings is selected as a target zero-peak setting with reference to the quality metric to insert the zero point according to the target zero-peak setting.

11. The envelope tracking calibration method according to claim 10, characterized in that: Calibrating this zero peak involves: The frequency of the zero point inserted by the zero peak is adjusted.

12. The envelope tracking calibration method according to claim 10, characterized in that: Calibrating this zero peak involves: The gain introduced by the zero point inserted by the zero-peak value is adjusted.

13. The envelope tracking calibration method according to claim 10, characterized in that: The quality metric includes an adjacent channel leakage ratio ACLR, and calculating the quality metric based on the RX baseband signal to calibrate the zero peak includes: Calculating the ACLR based on the RX baseband signal; and, The zero-peak value is adaptively calibrated according to the ACLR.

14. The envelope tracking calibration method according to claim 13, characterized in that: Adaptively calibrating the zero-peak value according to the ACLR includes: A zero-peak setting corresponding to a minimum ACLR value is selected from the plurality of predetermined zero-peak settings according to the ACLR as a target zero-peak setting for the zero-peak value.

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