RF Amplifier Distortion Correction via Down-Converted Error Signal
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Solution Overview
Problem
Current distortion correction techniques for microwave amplifiers, such as feed-forward, pre-distortion, adaptive bias, synthesis, and feedback methods, face limitations including poor efficiency, limited bandwidth, complexity, and limited effectiveness, which hinder the development of high-performance wireless devices with increased data rates and spectral efficiency.
Innovation Solution
A method and circuit that generate an error signal by combining a portion of the RF output signal with the RF input signal, down-converting, processing, and up-converting it to reduce distortion, while controlling the error signal generation based on its magnitude, thereby minimizing time delay and maintaining high gain in the RF signal path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If feed-forward distortion correction is used, then distortion is reduced, but time delay increases and efficiency decreases
Solution Approach 1:
The patent segments the distortion correction process into distinct functional blocks: error signal extraction, time delay adjustment, variable gain amplification, and signal combination. This segmentation allows independent optimization of each block, particularly enabling precise control of time delay to minimize loss while maintaining correction effectiveness.
Solution Approach 2:
The patent implements a feedback mechanism where the output signal is sampled, compared with the input signal to generate an error signal, and this error signal is then processed and fed back to correct the input. This closed-loop feedback approach enables dynamic adjustment of correction parameters based on actual distortion measurements, improving both accuracy and efficiency.
2Manufacturing precision
If feed-forward distortion correction is used, then distortion is reduced, but power consumption increases
Solution Approach 1:
The patent employs dynamic variable gain amplifiers that adjust their gain based on the magnitude of the error signal and operating conditions. This dynamic adjustment optimizes power consumption by using only the necessary amplification level required for effective distortion correction, rather than operating at fixed high gain levels continuously.
Solution Approach 2:
The patent changes key parameters including time delay, gain levels, and signal combination ratios to optimize the balance between distortion correction performance and power consumption. These parameter adjustments are made based on operating conditions to achieve efficient correction with minimal energy expenditure.
3Use of energy by moving object
If higher efficiency amplifiers are used, then power efficiency improves, but linearity deteriorates
Solution Approach 1:
The patent uses feedback to continuously monitor and correct the non-linear distortion introduced by high-efficiency amplifiers. By comparing the actual output with the expected linear output and generating an error signal, the system dynamically compensates for non-linearity, enabling high efficiency operation without sacrificing linearity performance.
Solution Approach 2:
The patent extracts the distortion component from the amplifier output by comparing it with the input signal, isolates this error signal, and processes it separately through variable gain amplification and time delay adjustment before combining it back with the main signal for correction.
4Device complexity
If distortion correction complexity is reduced, then device complexity decreases, but correction effectiveness is limited
Solution Approach 1:
The patent divides the distortion correction system into modular functional blocks: error extraction, time delay adjustment, variable gain control, and signal combination. This segmentation allows each block to be independently optimized and implemented with relatively simple circuitry, reducing overall device complexity while maintaining effective correction through the coordinated operation of all blocks.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces distortion in RF output signals, enhances bandwidth, and improves power efficiency, addressing the limitations of existing methods by providing a more efficient and effective linearization solution for microwave amplifiers.
Implementation Method 1
amplifying an applied RF input signal to generate an RF output signal with an amplifier
Implementation Method 2
modifying the error signal to generate a modified error signal, the modified error signal generated by down-converting the error signal
Implementation Method 3
up-converting the processed down-converted error signal
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.