RF Power Amplifier DPD Calibration Using Pulse-Step Sampling
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Solution Overview
Problem
Current digital predistortion (DPD) calibration techniques for RF power amplifiers in wireless communication devices are either too time-consuming or power-intensive, making them unsuitable for battery-operated devices, which is a challenge in maintaining PA linearity and reducing distortions while conserving power.
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 DPD calibration is performed using conventional techniques to maintain PA linearity and reduce distortions, then the linearity and distortion performance are improved, but the calibration time and power consumption increase significantly
Solution Approach 1:
The calibration process is segmented into discrete amplitude steps with silence gaps between them, allowing the calibration to be performed in manageable portions rather than as a continuous time-consuming process. Each amplitude step is calibrated independently, enabling faster overall calibration while maintaining precision.
Solution Approach 2:
The calibration uses periodic amplitude steps separated by silence gaps, creating a rhythmic calibration pattern that allows the system to maintain linearity measurements while reducing overall calibration time through efficient use of active and idle periods.
2Object-generated harmful factors
If DPD calibration is performed using conventional techniques to maintain PA linearity and reduce distortions, then the distortion levels are reduced, but the power consumption increases making it unsuitable for battery-operated devices
Solution Approach 1:
The calibration process divides the amplitude range into discrete steps with silence gaps, reducing the continuous power demand of conventional calibration methods. This segmentation allows the system to consume power in controlled bursts rather than continuously, making it suitable for battery-operated devices.
Solution Approach 2:
The calibration performs measurements at specific amplitude steps rather than continuously across the entire operating range, using partial action to achieve sufficient distortion reduction without the excessive power consumption of full continuous calibration.
3Use of energy by moving object
If the RF PA operates at high efficiency to conserve battery power, then power consumption is reduced, but nonlinear distortions increase degrading network performance
Solution Approach 1:
The system performs preliminary DPD calibration to pre-compensate for the nonlinear distortions that will occur when the PA operates at high efficiency. This preliminary action allows the PA to operate in its high-efficiency nonlinear region while the predistortion correction maintains signal quality and reduces distortions.
Solution Approach 2:
The calibration process uses feedback from the receiver circuitry to measure the actual distortions produced by the PA at different amplitude levels. This feedback is used to compute correction values that are applied to the transmitted signal, enabling the system to operate efficiently while maintaining low distortion levels.
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.