Digital Power Amplifier Pre-Distortion for Gain Error Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing Digital Power Amplifiers (DPAs) face efficiency optimization challenges that introduce distortion, particularly when input amplitude codes are large, due to variations in gain between different sections, leading to non-linear gain effects.
Innovation Solution
Implement pre-distortion modules to digitally correct the gain characteristic of DPAs by applying configured distortion to input signals, canceling non-linear gain effects and compensating for Phase Modulation-Amplitude Modulation (PM-AM) and Amplitude Modulation-Phase Modulation (AM-PM) distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If efficiency optimization techniques are applied in high power DPA, then power consumption is reduced, but distortion increases particularly when input amplitude codes are large
Solution Approach 1:
The patent applies pre-distortion to the input signal before it reaches the power amplifier. This preliminary action counteracts the expected non-linear gain effects, so that when the signal passes through the efficiency-optimized DPA, the pre-applied distortion cancellation results in a linear overall response, thereby maintaining low distortion while achieving high efficiency operation
Solution Approach 2:
The pre-distortion module applies an opposite distortion to the input signal that anticipates and counteracts the non-linear gain characteristics of the efficiency-optimized DPA. This preliminary anti-action ensures that the harmful distortion effects are canceled before they can manifest in the output, allowing the system to operate at high efficiency without introducing significant distortion
2Loss of energy
If multiple sections are used in DPA architecture, then efficiency is improved, but gain variation between sections causes non-linear effects
Solution Approach 1:
The patent applies different pre-distortion characteristics to different sections of the multi-section DPA. Each section receives a customized pre-distortion profile that compensates for its specific gain characteristics, ensuring that local variations in gain between sections are corrected individually, thereby maintaining overall linearity while preserving the efficiency benefits of the multi-section architecture
Solution Approach 2:
The patent dynamically adjusts the pre-distortion parameters based on the operating conditions and input signal characteristics. By changing the pre-distortion characteristics according to the specific gain variations observed in different sections under different operating conditions, the system maintains optimal linearity compensation across the full operating range while preserving efficiency
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
Systems and techniques are provided for power amplifier gain error compensation for a Digital Power Amplifier (DPA). In some aspects, a compensation method includes obtaining in-phase (I) and quadrature-phase (Q) components of a baseband sample corresponding to in-phase input amplitude codes and quadrature-phase input amplitude codes. The in-phase input amplitude codes can be distorted based on first gain pre-compensation information corresponding to an in-phase signal branch of the DPA, to generate pre-distorted output amplitude codes of the I component. The quadrature-phase input amplitude codes can be distorted based on second gain pre-compensation information corresponding to a quadrature-phase signal branch of the DPA, to generate pre-distorted output amplitude codes of the Q component. The DPA can be driven using the pre-distorted output amplitude codes of the I and Q components to generate a Radio Frequency (RF) output.