Digital Predistortion Calibration

Abstract

A method for digital pre - distortion (DPD) calibration in a wireless communication device is provided, the method comprising: transmitting (604) a plurality of pulses by a transmit circuit of the wireless communication device, wherein each pulse corresponds to an amplitude step in a pattern of amplitude steps, and wherein the amplitude steps are separated by silence gaps; receiving (605) each pulse in a receiver circuit of the wireless communication device; generating (606) accumulated samples for a pulse by an accumulator component of the wireless communication device based on a plurality of samples of each pulse output by the receiver circuit; and calculating (612) amplitude - related gain (AM / AM) and amplitude - related phase - shift (AM / PM) values of each accumulated sample by a processor of the wireless communication device.

Description

Background Art

[0001] Wireless sensor networks can be implemented using low-power single-chip devices (e.g., wireless communication devices) that rely on batteries. Such devices may include Wi-Fi radios with integrated radio frequency (RF) power amplifiers (PAs). The RF PA is an active component that generates high power levels and may need to operate efficiently to help save power. However, when using amplitude modulation signals, the efficient operation of the PA often results in nonlinear distortion, which degrades network performance. For this reason, regulatory requirements limit the amount of distortion that can be tolerated, which typically appears in the form of limiting the transmit power in adjacent channels. Given these requirements, it is important to improve PA linearity and reduce distortion.

[0002] One technique that can be used to improve PA linearity is digital predistortion (DPD) of the PA based on calibration parameters. DPD can be performed when the device is powered on or at other times. Current techniques for DPD calibration may be too time-consuming and / or consume too much power to be used in battery-powered devices. Summary of the Invention

[0003] Some embodiments relate to methods and apparatus for digital predistortion (DPD) calibration. In one aspect, a method for DPD calibration in a wireless communication device is provided, the method comprising: transmitting, by a transmit circuit of the wireless communication device, a plurality of pulses, wherein each pulse corresponds to an amplitude step in a pattern of amplitude steps, wherein the amplitude steps are separated by silence gaps; receiving, in a receiver circuit of the wireless communication device, each pulse; generating, by an accumulator component of the wireless communication device, accumulated samples for a pulse based on a plurality of samples of each pulse output by the receiver circuit; and calculating, by a processor of the wireless communication device, amplitude-dependent gain (AM / AM) and amplitude-dependent phase shift (AM / PM) values for each of the accumulated samples.

[0004] In one aspect, a wireless communication device is provided that includes a transmit circuit, a receiver circuit coupled to the transmit circuit via a feedback loop to receive pulses transmitted by the transmit circuit, an accumulator component coupled to the receiver circuit to receive samples output by the receiver circuit, a processor coupled to the transmit circuit and coupled to the accumulator component, and a non-transitory computer-readable storage medium storing a program for digital pre-distortion (DPD) calibration to be executed by the processor, the program including instructions for: transmitting, by the transmit circuit, a plurality of pulses, where each pulse corresponds to an amplitude step in a pattern of amplitude steps, where the amplitude steps are separated by silence gaps; receiving, via the feedback loop, each pulse in the receiver circuit; generating, by the accumulator component, accumulated samples for a pulse based on a plurality of samples of each pulse output by the receiver circuit; and calculating amplitude-dependent gain (AM / AM) and amplitude-dependent phase shift (AM / PM) values for each accumulated sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 is a block diagram of an exemplary 5 GHz band wireless local area network (WLAN) radio that includes circuitry for digital pre-distortion (DPD) and DPD calibration that can be used in a battery-powered wireless communication device;

[0006] Figure 2 is a graph depicting an amplitude ramp for DPD calibration;

[0007] Figure 3 is a graph of an exemplary pattern of interleaved high and low amplitude steps with silence gaps for DPD calibration;

[0008] Figure 4 is a graph of an exemplary pattern of seven interleaved high and low amplitude steps with silence gaps between the amplitude steps for DPD calibration;

[0009] Figure 5 shows Figure 1 is a block diagram of an exemplary WLAN radio showing additional details of the distortion estimation component of the WLAN radio;

[0010] Figure 6 is a flowchart of a method for DPD calibration;

[0011] Figure 7 is a block diagram of an exemplary wireless communication device; and

[0012] Figure 8 is a block diagram of an exemplary wireless sensor device. DETAILED DESCRIPTION

[0013] Specific embodiments will now be described in detail with reference to the accompanying drawings. For consistency, like elements in the various drawings are denoted by like reference numerals.

[0014] The embodiments provide calibration of digital pre-distortion (DPD) components in a Wi-Fi radio. The non-linear characteristics of a radio frequency (RF) power amplifier (PA) are characterized as the amplitude-dependent gain (amplitude modulation (AM) / AM or AM2AM) and the amplitude-dependent phase shift (AM / phase modulation (PM) or AM2PM) of the PA. The essence of digital pre-distortion is to pre-process the amplitude and phase of the input signal to compensate for the AM / AM and AM / PM distortions caused by the PA.

[0015] Figure 1 is a block diagram of an exemplary 5 GHz band wireless local area network (WLAN) radio 100 that includes circuitry for digital pre-distortion (DPD) and DPD calibration that can be used in a battery-powered wireless communication device. The exemplary radio 100 includes a transmit circuit 102 that includes a transmit (TX) analog circuit 103 and a power amplifier (PA) 106 coupled to the TX analog circuit 103. The TX analog circuit 103 includes circuitry for preparing a signal to be transmitted for amplification by the PA 106. The exemplary radio 100 also includes an auxiliary receiver circuit 104 that is coupled to the transmit circuit 102 via a feedback loop 112 for determining DPD calibration parameters of the PA 106. The input to the radio 100 is the in-band (I) and quadrature (Q) components of the RF signal to be transmitted.

[0016] In view of efficiency in terms of power consumed and power delivered, the PA 106 can operate near its saturation point (PSAT). However, operating the PA near PSAT introduces non-linear distortion at the output of the PA and degrades the bit error rate (BER) performance. To compensate for the AM / AM and AM / PM distortions caused by the PA 106 when operating near PSAT, the I and Q signals are pre-distorted by a DPD component 108. The DPD component 108 includes a complex gain regulator that controls the amplitude and phase of the input signal. The amount of pre-distortion is controlled by an entry in a calibration look-up table that interpolates the AM / AM and AM / PM non-linearities of the PA 106. In other words, the amount of pre-distortion is controlled by the correction values of the AM / AM and AM / PM non-linearities of the PA 106 stored in the calibration look-up table. The envelope level of the input signal is used to index the calibration look-up table. The complex gain regulator provides non-linear characteristics that are opposite to the non-linear characteristics of the PA 106 according to the correction values given by the entries in the calibration look-up table.

[0017] The correction value of an entry in the lookup table is determined by a calibration process performed using the auxiliary receiver circuit 104 to characterize the PA 106. The calibration is performed when the radio 100 is powered on. The calibration can also be performed during the operation of the radio 100, for example, periodically, to accommodate changes in the characteristics of the PA 106 due to factors such as temperature variations, voltage variations, channel variations, and aging.

[0018] In one calibration method, a continuous wave (CW) tone with a continuous ramp amplitude is transmitted by the transmit circuit 102 and fed back from the output of the PA 106 to the input of the auxiliary receiver circuit 104 via the feedback loop 112. The number of amplitude steps in the continuous ramp can be determined based on the characteristics of the PA 106. Figure 2 The graph of illustrates an example of such an amplitude ramp. The distortion estimation component 110 receives the digital signal output by the auxiliary receiver circuit 104 at each step and estimates the AM / AM and AM / PM values representing the distortion introduced by the PA at the corresponding amplitude. Then, the estimated AM / AM and AM / PM values of the amplitude steps are used to determine the correction entries of the calibration lookup table used by the DPD component 108.

[0019] The AM / AM and AM / PM values are estimated for each step in the continuous ramp as follows. At each amplitude step, a number of samples of a complex CW tone are transmitted at that amplitude and received in the auxiliary receiver circuit 104. An accumulated sample for the amplitude is generated based on the samples output by the auxiliary receiver circuit 104. Typically, the output samples are downconverted to baseband, and after the auxiliary receiver circuit 104 has output a specified number of samples and those specified number of samples have been downconverted, a filter is applied to the downconverted samples to generate the accumulated sample. The magnitude and angle of the accumulated sample represent the AM / AM and AM / PM of that step, respectively.

[0020] For example, to downconvert the output samples to baseband, the output samples can be matched in delay with the corresponding samples input to the transmit circuit 102 and then multiplied by the complex conjugate of the corresponding input samples. Also, to generate the accumulated sample, an averaging filter can be applied to the downconverted samples.

[0021] Using a CW tone with a continuous ramp involves increasing current, which can lead to power management failures when the battery of a wireless communication device cannot supply the required current. For example, at high current demands, the battery voltage may drop below the safety margin of the voltage sensor in the device, causing the device to shut down. In some embodiments, instead of transmitting a continuous CW tone with multiple increasing amplitude steps, a pattern of amplitude steps separated by silence gaps is transmitted. This pattern may be referred to herein as the transmission pattern. Breaking the ramp continuous tone with silence gaps avoids continuous current surges from the battery and allows the bypass capacitor of the battery to recharge and supply current for the next amplitude step while avoiding battery voltage drop.

[0022] When performing DPD calibration, network traffic may be interrupted for the duration of the calibration. Adding silence gaps between amplitude steps may unacceptably increase the amount of time required for calibration, thus requiring a trade-off among the number of amplitude steps, the pulse width of each step (also referred to as the number of samples in the pulse), and the length of the silence gap between amplitude steps. For example, assuming 64 amplitude steps, a pulse width of approximately 2 us, and a silence gap length of approximately 10 us, the calibration time will be greater than 750 us.

[0023] The pulse width and amplitude of the amplitude steps, the pattern or ordering of the amplitude steps, the number of samples per pulse, and the length of the silence gap can be determined empirically. To determine the transmission pattern of the amplitude steps, the pulse width and amplitude of each amplitude step, the sampling of each pulse, and the length of the silence gap, three metrics can be considered: transmission performance, calibration time, and power consumption. In terms of performance, two metrics are considered: error vector magnitude (EVM) and spectral mask. The goal is to find the optimal pulse width and silence gap length, as well as a transmission pattern that reduces battery current consumption while minimizing the calibration time and not violating the EVM and spectral mask metrics.

[0024] In some embodiments, the transmission pattern of the amplitude steps and silence gaps is a pattern in which the amplitude of each amplitude step increases from the previous amplitude step. Although this pattern may increase the current demand for continuously increasing pulse amplitudes, if the length of the silence gap between amplitude steps is long enough to allow the bypass capacitor of the battery to recharge, the current demand may not be a problem. However, using a long enough silence gap length may unacceptably increase the time required for calibration. In some embodiments, the transmission pattern is a pattern in which high and low amplitude steps are interleaved, i.e., alternating, with silence gaps between the amplitude steps. Interleaving reduces the length of the silence gap required for recovery, thus reducing the calibration time for the same number of amplitude steps. Figure 3 Is a graph showing an example of a pattern of interleaved high and low amplitude steps with silence gaps between the amplitude steps.

[0025] In some embodiments, the number of amplitude steps in the transmit mode is equal to the number of entries in the calibration look-up table. However, the slow-changing nature of the AM / AM curve can be utilized to further reduce the number of transmit amplitude steps used for calibration, thereby reducing the calibration time. In some embodiments, to reduce the time required for calibration, the number of transmit amplitude steps is less than the number of calibration look-up table entries. For example, compared to thirty-two table entries, the number of amplitude steps is seven, and the other AM / AM and AM / PM values required to determine the correction values for the calibration look-up table entries are interpolated from the AM / AM and AM / PM values calculated from the accumulated samples for the fewer number of amplitude steps.

[0026] For example, if the calibration look-up table has thirty-two entries and the transmit mode is seven amplitude steps at selected amplitudes represented in the look-up table, the AM / AM and AM / PM values for determining the other twenty-five table entries are interpolated from the AM / AM and AM / PM values calculated from the seven accumulated samples for the seven amplitude steps. In such embodiments, the number of amplitude steps and the amplitudes can be determined empirically, along with the pulse width, the silence gap length, and the transmit mode. Figure 4 Graph showing an example of a transmit mode with seven interleaved high and low amplitude steps with a silence gap between the amplitude steps.

[0027] Figure 5 Shows Figure 1 Block diagram of an example WLAN radio 500 showing additional details of the distortion estimation component 110. The distortion estimation component 110 includes a calibration tone generator 513, a processor 510, and an accumulator component 514. The DPD calibration process is controlled by calibration software executed on the processor 510. The processor 510 includes one or more suitable processors, such as a programmable general or special-purpose microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable controller, a programmable logic device (PLD), etc., or a combination of such devices. Software instructions for performing the calibration process in the radio 100 to generate the entries in the calibration look-up table for the DPD component 108 are stored in a non-transitory computer-readable storage medium (not shown), such as random access memory (RAM), read-only memory (ROM), and flash memory.

[0028] The multiplexer 509 selects between the input I and Q signals and the signal from the calibration tone generator 513 based on a control signal set by the processor 510. The calibration tone generator 513 includes a programmable circuit to generate tones (pulses) with configurable duration and amplitude.

[0029] The accumulator component 514 includes programmable circuitry to down-convert and accumulate a specified number of samples of the transmitted pulses output from the auxiliary receiver circuit 104. The accumulator component 514 further includes circuitry for filtering the down-converted samples to generate accumulated samples of the transmitted pulses and providing the accumulated samples to the processor 510.

[0030] In some embodiments, an additional reduction in current consumption is achieved by disabling one of the quadrature channels of the auxiliary receiver circuit 104 during DPD calibration. Either quadrature channel can be disabled, which can reduce the current consumption by approximately 50% when processing the received signal. When only one quadrature channel is used, the levels of the image tone and the original tone are equal. The accumulator component 514 is designed to eliminate the frequency of the image tone because if the level of the image tone is high, the quality of the original signal may be negatively affected.

[0031] In such embodiments, the transmitted tone frequency and the number of accumulated samples for each amplitude step are selected such that the zeros in the frequency response of the filter used by the accumulator component 514 are multiples of the tone frequency, thereby eliminating the image tone. Additionally, the frequency of the digital clock affects the selection of the tone frequency and the number of samples to be accumulated. For example, assume the clock frequency is 80 MHz and the number of samples is 64. Given these assumptions, the lowest possible frequency that can be resolved is 80e6 / 64 = 1.25 MHz. Finer frequency resolution can be achieved by accumulating more samples.

[0032] Figure 6 is executable by Figure 1 the WLAN radio 100 and Figure 5 the WLAN radio 500 for DPD calibration. The method assumes a predefined transmission pattern for the amplitude steps, where the pulse width, amplitude, silent gap length, and the number of samples to be accumulated are specified for each step. In some embodiments, for each step of the transmission pattern, the width of the pulse is the same, the silent gap length is the same, and the number of samples to be accumulated is the same. In some embodiments, the pulse width, silent gap length, and / or the number of samples to be accumulated can vary with the steps in the transmission pattern. In some embodiments, the transmission pattern is such that the high and low amplitude steps are interleaved, i.e., an alternating transmission pattern. In some embodiments, one of the channels of the auxiliary receiver circuit 104 is disabled.

[0033] For each pulse in the transmit mode, calibration software 600 executed on processor 510 configures tone generator 513 to generate a pulse of a specified width and amplitude, and also configures 602 accumulator component 514 to accumulate samples of a specified number of pulses. Samples of the pulse are transmitted 604 via transmit circuit 102 and received 605 in auxiliary receiver circuit 104 via feedback loop 112.

[0034] Accumulator component 514 receives the samples output by auxiliary receiver circuit 104 and generates 606 an accumulated sample from the specified number of samples. Generation of the accumulated sample includes downconverting each output sample to baseband and, after the specified number of samples have been received, filtering the samples to determine the accumulated sample. In some embodiments, an averaging filter is used to determine the accumulated sample. The accumulated sample is then provided to processor 510.

[0035] If the pulse is not the last pulse 608 in the transmit mode, the calibration software waits 610 until a specified silent gap length has elapsed and then repeats steps 600 - 606 for the next pulse in the transmit mode. Once the last pulse 608 has been transmitted, the calibration software calculates 612 the AM / AM and AM / PM values of each accumulated sample and calculates 614 a correction value for a calibration look-up table entry based on the AM / AM and AM / PM values of the accumulated sample. The correction value is stored in the corresponding calibration look-up table location and is used by DPD component 108 during normal operation of WLAN radio 100. In some embodiments, the transmit mode includes fewer transmit amplitude steps than are required to determine the calibration look-up table entries. In such embodiments, additional AM / AM and AM / PM values are interpolated from the AM / AM and AM / PM values calculated for the accumulated samples generated by the transmit mode.

[0036] Figure 7 is a simplified block diagram of an example wireless communication device 700. Wireless communication device 700 includes antenna 701, transceiver component 702, processor component 704, memory component 706, and application component 708. Antenna 701 is configured to receive and transmit radio frequency (RF) signals. Transceiver component 702 is configured to modulate received RF signals and modulate RF signals to be transmitted. Transceiver component 702 is further configured to perform DPD and DPD calibration as described herein. For example, transceiver component 702 may include circuitry for DPD and DPD calibration, such as Figure 1 and Figure 5The circuit. The memory component 706 can include any suitable memory, such as random access memory (RAM), read-only memory (ROM), flash memory, etc., or a combination of such memories. The memory component 706 can be a non-transitory computer-readable storage medium storing programs for execution by the processor component 704. The application component 708 is configured to perform the functions of the wireless communication device 700, such as controlling alarms, controlling lights, temperature sensing, etc.

[0037] The processor component 704 includes one or more suitable processors, such as programmable general or special microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable controllers, programmable logic devices (PLDs), etc., or a combination of such devices.

[0038] Figure 8 is a simplified block diagram of an example system-on-chip (SOC) 800 (e.g., a wireless communication device), which can be configured to perform DPD calibration as described herein. The depicted example SOC 800 is the CC3220x SimpleLink available from Texas Instruments (TI) TM Wireless microcontroller unit (MCU) system-on-chip (SOC), which can include support for DPD calibration as described herein. A brief description of the CC3220 is provided herein. Texas Instruments (TI) in its publication SWAS035A, September 2016 (revised February 2017), “CC3220 SimpleLink TM Wireless and Internet-of-Things Solution, a Single-Chip Wireless MCU (CC3220 SimpleLink TM Wireless and Internet-of-Things Solution, a Single-Chip Wireless MCU)”, provides a detailed description of the CC3220x, the entire content of which is incorporated herein by reference.

[0039] The SOC 800 provides two execution environments, a user application environment implemented by the application MCU subsystem 802 and a network environment implemented by the network processor subsystem 804 that executes the Wi-Fi and Internet logical layers. The application MCU subsystem 802 incorporates an MCU as the main processor, which has embedded random access memory (RAM) and optional integrated flash memory. The network processor subsystem 804 incorporates on-chip WI-FI Internet TM (WI-FI Internet-on-a-chip TM)A dedicated ARM MCU and Wi-Fi transceiver circuit. In some embodiments, the Wi-Fi transceiver circuit includes circuits for DPD and DPD calibration, such as Figure 1 and Figure 5 circuits.

[0040] The SOC 800 also incorporates a RAM 814 and a ROM 816. The RAM 814 can be used to store both application data and execute application code. The SOC 800 also incorporates a peripheral interface 806, such as a camera interface and interfaces for Serial Peripheral Interface (SPI), Inter-Integrated Circuit (I 2 C), Secure Digital (SD) memory, Inter-IC Sound (I2S), and Universal Asynchronous Receiver-Transmitter (UART) protocols. The analog interface 808 in the SOC 800 includes an Analog-to-Digital Converter (ADC) and Pulse-Width Modulation (PWM). The SOC 800 also includes a power management subsystem 812 and system support circuits 810, such as oscillators, General-Purpose Input / Output (GPIO) pins, timers, and Internal Direct Memory Access (DMA).

[0041] Software instructions for implementing DPD calibration as described herein can be stored in a computer-readable medium such as Random Access Memory (RAM) 814 or Read-Only Memory (ROM) 816 on the SOC 800 or in the ROM in the network processor subsystem 804 and executed by a processor in the network processor subsystem 804.

[0042] Other embodiments

[0043] Although this specification contains a limited number of embodiments, those who benefit from this specification will understand that other embodiments can be designed without departing from the scope of this specification.

[0044] Embodiments are described herein in which some functions of DPD calibration are performed by a processor executing software instructions. In other embodiments, some or all of these functions can be performed in a hardware accelerator.

[0045] Embodiments are described herein in which an application average filter is applied to generate accumulated samples. Other suitable filters can also be used.

[0046] In some embodiments, the length of the silent gap between pulses has different lengths to avoid emitting periodic pulses that can be detected as radar signals. For example, each different gap length can be randomly selected or set in the transmit mode.

[0047] The embodiments are described with reference to a single calibration lookup table. In some embodiments, there are separate calibration tables for AM / AM correction values and AM / PM correction values. In some embodiments, there are multiple AM / AM and AM / PM calibration lookup tables corresponding to different gain settings of the transmit circuit.

[0048] Embodiments are described in which each step of the transmit mode has a different amplitude. In other embodiments, some amplitude steps may have the same amplitude. For example, a smaller pulse width may be used for high amplitude steps because such amplitude steps have a high SNR. However, lower amplitude steps have a lower SNR and require a larger pulse width to obtain a more accurate filtering result. To reduce the current consumption of the lower amplitudes that require a larger pulse width, multiple amplitude steps with a smaller pulse width and a silent gap between the pulses having the same amplitude may be transmitted instead of transmitting a single large pulse.

[0049] Accordingly, it is expected that the appended claims will cover any such modifications of the embodiments that fall within the true scope of the specification.

Claims

1. A method for digital pre - distortion calibration, i.e., DPD calibration, in a wireless communication device, the method comprising: Transmitting, by a transmit circuit of the wireless communication device, a plurality of pulses, wherein each pulse corresponds to an amplitude step in a pattern of amplitude steps, the pattern of amplitude steps comprising a first set of amplitude steps alternating with a second set of amplitude steps, wherein the amplitude steps are separated by silent gaps and wherein the amplitudes of the first set of amplitude steps increase with time and the amplitudes of the second set of amplitude steps decrease with time; Receiving, in a receiver circuit of the wireless communication device, each pulse; Generating, by an accumulator component of the wireless communication device, accumulated samples for each pulse based on a plurality of samples of each pulse output by the receiver circuit; and Calculating, by a processor of the wireless communication device, amplitude - related gain and amplitude - related phase - shift values, i.e., AM / AM and AM / PM values, for each accumulated sample.

2. The method according to claim 1, wherein Generating the accumulated samples further comprises down - converting and filtering the plurality of samples of each pulse to determine the accumulated samples of the pulse.

3. The method according to claim 1, wherein At least one of the silent gaps has a length different from that of other silent gaps.

4. The method according to claim 1, wherein At least one pulse comprises a different number of samples than other pulses.

5. The method according to claim 1, wherein Determining the length of the silent gaps, the pattern of the amplitude steps, the number and amplitude of the amplitude steps, and the number of samples in the pulses based on battery current consumption, calibration time, and error vector magnitude and spectral mask metrics.

6. The method according to claim 1, further comprising calculating correction values for calibration look - up table entries based on the calculated AM / AM and AM / PM values.

7. The method according to claim 6, wherein, The pattern of the amplitude steps consists of the same number of amplitude steps as the number of calibration look - up table entries.

8. The method according to claim 6, wherein The pattern of the amplitude steps comprises fewer amplitude steps than the number of calibration look - up table entries, and calculating the correction values further comprises interpolating additional AM / AM and AM / PM values for calculating the correction values based on the calculated AM / AM and AM / PM values.

9. The method according to claim 8, wherein The pattern of the amplitude steps consists of seven amplitude steps, the lengths of the silent gaps between the amplitude steps being the same, and the number of samples in the plurality of samples of the pulse for generating the accumulated samples of the pulse being the same for each pulse.

10. The method according to claim 1, further comprising disabling the quadrature channels of the receiver circuit.

11. A wireless communication device, comprising: A transmit circuit; A receiver circuit coupled to the transmit circuit through a feedback loop, the receiver circuit for receiving pulses transmitted by the transmit circuit; An accumulator component coupled to the receiver circuit to receive the samples output by the receiver circuit; A processor coupled to the transmit circuit and coupled to the accumulator component; And A non - transitory computer - readable storage medium storing a program for digital pre - distortion calibration, i.e., DPD calibration, for execution by the processor, the program comprising instructions for: Multiple pulses are transmitted by the transmission circuit, where each pulse corresponds to an amplitude step in a pattern of amplitude steps, the pattern of amplitude steps comprising a first set of amplitude steps alternating with a second set of amplitude steps, where the amplitude steps are separated by silence gaps and where the amplitudes of the first set of amplitude steps increase with time and the amplitudes of the second set of amplitude steps decrease with time; Each pulse is received in the receiver circuit via the feedback loop; The accumulator component generates accumulated samples for the pulse based on multiple samples of each pulse output by the receiver circuit; and Calculate the amplitude-dependent gain and amplitude-dependent phase shift values, i.e., AM / AM and AM / PM values, of each accumulated sample.

12. The wireless communication device according to claim 11, wherein, The multiple samples of each pulse are down-converted and filtered by the accumulator component to determine the accumulated samples of the pulse.

13. The wireless communication device according to claim 11, wherein, At least one of the silence gaps has a different length from the other silence gaps.

14. The wireless communication device according to claim 11, wherein, At least one pulse includes a different number of samples from the other pulses.

15. The wireless communication device according to claim 11, wherein, Determine the length of the silence gap, the pattern, number and amplitude of the amplitude steps, and the number of samples in the pulse based on battery current consumption, calibration time, and error vector magnitude and spectral mask metrics.

16. The wireless communication device according to claim 11, wherein, The instructions further include instructions for calculating correction values for calibration look-up table entries based on the calculated AM / AM and AM / PM values.

17. The wireless communication device according to claim 16, wherein, The pattern of amplitude steps consists of the same number of amplitude steps as the number of calibration look-up table entries.

18. The wireless communication device according to claim 16, wherein, The pattern of amplitude steps includes fewer amplitude steps than the number of calibration look-up table entries, and the additional AM / AM and AM / PM values required for calculating the correction values are interpolated from the calculated AM / AM and AM / PM values.

19. The wireless communication device according to claim 18, wherein, The pattern of amplitude steps consists of seven amplitude steps, the length of the silence gap between the amplitude steps is the same, and the number of samples in the multiple samples of the pulse for generating the accumulated samples of the pulse is the same for each pulse.

20. The wireless communication device according to claim 11, wherein, Disable the quadrature channels of the receiver circuit during the DPD calibration.

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