Class G RF Power Amplifier Baseband Linearization for Gain-Phase Distortion
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Solution Overview
Problem
Class G radiofrequency power amplifiers experience significant distortions due to gain and phase variations with different supply voltages, leading to signal transmission errors and channel scrambling, which existing linearization techniques, such as predistortion methods, are unable to effectively address.
Innovation Solution
A baseband linearization system comprising a digital filter with complex coefficients and a digital predistortion module, which adjusts power supply voltages and compensates for distortions by extracting and refining predistortion and filter coefficients, ensuring constant power gain and phase shift across all operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If class G power amplifier uses multiple discrete supply voltages to improve efficiency, then energy efficiency is improved, but signal distortion increases due to gain and phase variations
Solution Approach 1:
The system performs preliminary digital predistortion on the input signal before amplification, pre-compensating for the non-linear gain and phase variations that will occur when switching between discrete supply voltages. This anticipatory correction ensures that the output signal remains linear despite the efficiency-optimized switching operation.
Solution Approach 2:
The system implements feedback mechanisms that monitor the actual gain and phase variations across different supply voltage levels, then dynamically adjust the predistortion parameters to compensate for these variations. This closed-loop control maintains signal linearity while preserving the efficiency benefits of class G operation.
2Manufacturing precision
If predistortion methods are used to correct gain variations, then linearity is improved, but they fail to address phase shift variations in class G amplifiers
Solution Approach 1:
The linearization system is designed to perform both gain compensation and phase compensation through a unified digital signal processing architecture. The same predistortion processor handles both amplitude and phase corrections simultaneously, making the system universally effective for class G amplifiers where traditional predistortion only addressed gain variations.
Solution Approach 2:
The system extends the traditional one-dimensional gain predistortion approach into a two-dimensional correction space that includes both magnitude and phase components. By adding the phase dimension to the predistortion processing, the system comprehensively addresses all sources of signal distortion in class G amplifiers.
3Adaptability or versatility
If supply voltage switching is performed to adapt to different power levels, then adaptability is improved, but transient distortions occur during voltage transitions
Solution Approach 1:
The system applies predistortion correction before the supply voltage switching occurs, preparing the signal in advance to compensate for the upcoming transition. This preliminary processing ensures that even during transient voltage changes, the output signal maintains integrity without introducing additional distortions.
Solution Approach 2:
The linearization system incorporates cushioning measures by pre-calculating and applying compensation parameters that anticipate the effects of voltage transitions. This prior cushioning protects the signal from transient distortions that would otherwise occur during supply voltage switching events.
Data Source
AI summary
Disclosed is a system and a method of baseband linearization for a class G radiofrequency power amplifier, the linearization system including a module for selecting the amplifier power supply voltage, a digital predistortion module, and a module for extracting predistortion coefficients, wherein the linearization system also includes a digital filter with complex coefficients, the input of which is connected to the output of the digital predistortion module, and a module for extracting filter coefficients which is designed to extract filter coefficients used by the digital filter with complex coefficients.