DPD Calibration Pulses for Faster PA Linearity Correction
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Solution Overview
Problem
Current digital predistortion (DPD) calibration techniques for RF power amplifiers in wireless communication devices are too time-consuming and power-intensive, making them unsuitable for battery-operated devices, which often experience nonlinear distortions that degrade network performance.
Innovation Solution
A method and apparatus for DPD calibration that involves transmitting a pattern of amplitude steps with silence gaps, using an accumulator component to generate accumulated samples, and computing amplitude-dependent gain and phase shift values, allowing for efficient calibration of the RF power amplifier while minimizing power consumption and calibration time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional DPD calibration techniques are used, then PA linearity is improved, but calibration time and power consumption increase significantly
Solution Approach 1:
The patent applies periodic action by using pulsed calibration signals with alternating active and idle periods. The calibration is performed in periodic bursts rather than continuously, where the device transmits calibration pulses periodically and remains in low-power mode during idle periods. This reduces overall calibration time and power consumption while maintaining PA linearity correction effectiveness.
Solution Approach 2:
The calibration process is segmented into multiple discrete amplitude steps rather than a continuous sweep. The patent divides the calibration range into specific amplitude levels (e.g., 0 dBm, 10 dBm, 20 dBm, 30 dBm) and performs calibration at each segment independently. This segmentation allows for faster, more efficient calibration that reduces total time while maintaining accuracy.
2Manufacturing precision
If traditional DPD calibration techniques are used, then PA linearity is improved, but battery power consumption increases
Solution Approach 1:
The system uses periodic calibration bursts followed by low-power idle periods. During calibration, the device transmits pulsed signals at specific amplitude levels and then enters a low-power state. This periodic operation pattern significantly reduces average battery current consumption compared to continuous calibration, while still achieving the necessary PA linearity correction.
Solution Approach 2:
The patent employs short-duration calibration pulses instead of continuous calibration signals. Each calibration pulse is a brief, high-power event followed by a longer low-power period. These short-lived calibration events are sufficient to update DPD parameters without sustaining high power consumption, effectively using brief energy bursts to achieve the calibration goal.
3Productivity
If amplitude steps are transmitted continuously without gaps, then calibration speed is improved, but power consumption and signal distortion increase
Solution Approach 1:
The calibration signals are transmitted as periodic pulses with deliberate gaps between them. Each pulse represents a specific amplitude step, and the periodic gaps allow the PA to settle and reduce inter-modulation distortion. This periodic transmission pattern maintains calibration speed by keeping pulses closely spaced while eliminating harmful continuous transmission effects.
Solution Approach 2:
The patent skips through calibration amplitude steps using discrete pulses rather than continuous sweeping. Each pulse rapidly transitions to the next amplitude level, rushing through the calibration process efficiently. The gaps between pulses are minimal but sufficient to prevent distortion buildup, allowing the system to skip through calibration quickly without sacrificing accuracy.
Data Source
AI summary
A method for digital predistortion (DPD) calibration in a wireless communication device is provided that includes transmitting, by transmission circuitry of the wireless communication device, 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 each pulse in receiver circuitry of the wireless communication device, generating, by an accumulator component of the wireless communication device, an accumulated sample for each pulse based on a plurality of samples output by the receiver circuitry for the pulse, and computing, by a processor of the wireless communication device, amplitude dependent gain (AM/AM) and amplitude dependent phase shift (AM/PM) values for each accumulated sample.