RF Amplifier Distortion Correction via Digital Feedback
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Solution Overview
Problem
Current distortion correction techniques for microwave amplifiers in wireless devices face limitations such as poor efficiency, limited bandwidth, complexity, and limited effectiveness, which hinder the achievement of high power efficiency and wide bandwidth support in modern wireless protocols.
Innovation Solution
A microwave processor is used to divide input and output signals into primary and secondary components, generating an error signal that is processed to reduce distortion through vector demodulation and feedback mechanisms, minimizing time delay and maintaining RF signal gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If non-linear amplifier classes (C, D, E, F) are used to achieve high power efficiency, then power efficiency is improved, but distortion is generated in the output signal
Solution Approach 1:
The patent implements a feedback mechanism where the output signal is sampled, processed through a digital signal processor to generate correction signals, and fed back to the amplifier input. This closed-loop feedback system continuously monitors and corrects distortion while maintaining high efficiency operation of non-linear amplifier classes
Solution Approach 2:
The patent segments the distortion correction function into separate modular components: output signal sampling, digital signal processing for error detection, correction signal generation, and feedback combination. This segmentation allows independent optimization of each component while maintaining overall system efficiency
2Object-generated harmful factors
If feed-forward distortion correction is implemented, then distortion is reduced, but system complexity and power consumption increase
Solution Approach 1:
The patent replaces complex analog feed-forward correction circuits with a digital signal processing approach. The digital signal processor implements distortion correction algorithms in the digital domain, substituting complex analog component networks with programmable digital logic that achieves similar or better performance with reduced hardware complexity
3Object-generated harmful factors
If distortion correction circuits are added to maintain linearity, then distortion is reduced, but power efficiency decreases
Solution Approach 1:
The patent applies preliminary digital signal processing to the output signal to predict and calculate correction signals before they are applied to the amplifier input. This preliminary processing allows the system to prepare correction signals in advance, enabling high efficiency amplification with pre-calculated distortion compensation rather than requiring continuous high-power correction circuitry
4Adaptability or versatility
If wide bandwidth is supported for modern wireless protocols, then adaptability is improved, but distortion and power consumption increase
Solution Approach 1:
The patent implements dynamic distortion correction that adapts to different bandwidth requirements and operating conditions. The digital signal processor dynamically adjusts correction parameters and processing depth based on the specific wireless protocol and bandwidth being used, optimizing performance for each mode while maintaining low distortion across wide bandwidth ranges
Data Source
AI summary
A method of reducing distortion in the output of an amplifier is provided. The method comprises subtractively combining an error signals with the appropriate phase shift with input signals to be amplified. The error signal being generated by subtractively combining a fed-forward portion of the input signal with a portion of the fed-back amplified output signal, and signal processing applied to it between its generation and application to correcting the input signal in the baseband domain. The error therefore being down-converted, filtered, and up-converted in the feedback path. The filtered baseband error signal components providing inputs to a controller which adjusts active elements of the amplification and feedback path in order to minimize the distortion within the output of the amplifier.