Baseband Linearization for Class G RF Amplifier Distortion Control
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Solution Overview
Problem
Class G radio frequency power amplifiers experience significant distortions due to variations in gain and phase across different supply voltages, leading to signal transmission errors and adjacent channel interference, which existing linearization techniques, such as pre-distortion methods, are unable to effectively address.
Innovation Solution
A baseband linearization system incorporating a digital filter with complex coefficients is implemented at the output of a digital pre-distortion module to cancel distortions induced by Class G operation, ensuring constant power gain and phase shift across all supply voltages and eliminating spectral noise across the entire instantaneous bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If Class G power amplifier operation with multiple discrete supply voltages is used, then power amplifier efficiency is greatly improved, but significant distortions are introduced due to gain and phase variations between different supply voltages
Solution Approach 1:
The patent applies pre-distortion techniques where the input signal is pre-modified before amplification to compensate for the expected gain and phase variations that will occur during Class G operation. This preliminary action counteracts the distortions that would otherwise be generated by the switching between different supply voltages, allowing the amplifier to maintain both high efficiency and signal fidelity
2Object-generated harmful factors
If pre-distortion methods are used for linearization, then some distortion compensation is achieved, but they cannot effectively address the specific distortions introduced by Class G operation modes
Solution Approach 1:
The patent implements a supply voltage selection module that dynamically changes the operating parameters (supply voltage levels) based on the instantaneous power requirements. Combined with adaptive pre-distortion that adjusts its compensation characteristics according to the selected supply voltage, this allows the system to maintain optimal linearity across all operating conditions while preserving the efficiency benefits of Class G operation
3Productivity
If Class G amplification technique is used, then system efficiency is improved for very wide modulation bandwidths, but significant distortions occur that require coupling with linearization techniques
Solution Approach 1:
The patent introduces a digital signal processing intermediary consisting of the supply voltage selection module and the pre-distortion module. This intermediary sits between the input signal and the Class G amplifier, preparing the signal in advance to compensate for the amplifier's non-linearities. This allows the system to maintain high efficiency while effectively eliminating distortions through the mediating action of the digital processing stage
Data Source
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AI summary
The invention relates to a system and a method of baseband linearisation (2) for a class G radiofrequency power amplifier (3), said linearisation system (2) comprising a module for selecting the amplifier power supply voltage (11), a digital predistortion module (12), and a module for extracting predistortion coefficients (15), characterised in that said linearisation system (2) also comprises a digital filter (13) with complex coefficients, the inlet of which is connected to the outlet of the digital predistortion module (12), and a module for extracting filter coefficients (16) which is designed to extract filter coefficients (16a) used by the digital filter with complex coefficients (13).