Power Amplifier IM3 Cancellation Using Anti-Phase Distortion
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Solution Overview
Problem
Existing power amplifiers in radio communication systems suffer from unnecessary power loss and signal distortion due to the need for error amplifiers and delay circuits in feed-forward amplifiers, and the generation of third-order intermodulation distortion in high-efficiency amplifiers, leading to reduced efficiency and linearity.
Innovation Solution
A power amplifier design that includes a distributor, an anti-phase third-order intermodulation distortion generation circuit, and two amplifiers to generate and offset third-order intermodulation distortion, reducing power loss and distortion while maintaining high efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If feed-forward amplifier structure is used to reduce distortion, then distortion compensation is improved, but power loss increases due to error amplifier and delay circuit
Solution Approach 1:
The invention extracts only the necessary distortion compensation function from the complex feed-forward amplifier structure. By using a simple amplifier operating in a nonlinear region to generate third-order intermodulation distortion, the patent removes the need for error amplifiers and delay circuits, achieving distortion compensation with minimal power loss.
Solution Approach 2:
The invention converts the harmful third-order intermodulation distortion, which is normally considered a detrimental effect to be eliminated, into a beneficial component. By deliberately generating this distortion in a controlled manner and combining it with the main signal, the patent achieves distortion compensation without requiring additional power-consuming components.
2Loss of energy
If high-efficiency amplifier is used to reduce power loss, then power efficiency is improved, but third-order intermodulation distortion increases
Solution Approach 1:
The invention transforms the harmful third-order intermodulation distortion generated by high-efficiency amplifiers into a useful component for distortion compensation. By controlling the amplifier to operate in a nonlinear region, the patent generates the desired distortion products that can be combined with the main signal to cancel out unwanted distortion.
Solution Approach 2:
The invention changes the operating parameters of the amplifier, specifically allowing it to operate in a nonlinear region rather than maintaining strict linearity. This parameter change enables the amplifier to generate controlled third-order intermodulation distortion while maintaining high efficiency, resolving the contradiction between power efficiency and distortion generation.
3Device complexity
If simple amplifier structure is used to reduce circuit scale, then device complexity is reduced, but distortion compensation capability is insufficient
Solution Approach 1:
The invention enables the amplifier to perform distortion compensation on its own without requiring separate error amplifiers or complex feedback circuits. By operating in a nonlinear region and generating controlled third-order intermodulation distortion, the simple amplifier structure achieves distortion compensation capability inherently, eliminating the need for additional compensation components.
Data Source
AI summary
A power amplifier of the present invention includes a distributor (76) for distributing an input signal; an anti-phase third-order intermodulation distortion generation circuit (63) for, upon receiving the input signal that was distributed by the distributor, generating third-order intermodulation distortion for which the phase difference is anti-phase with respect to each of two main signals of different frequencies and supplying the two main signals and the third-order intermodulation distortion; a first amplifier (61) for amplifying the signal received from the anti-phase third-order intermodulation distortion generation circuit and supplying the result; a second amplifier (62) for amplifying the input signal that was distributed by the distributor and supplying the result; and a synthesizer (64) for combining the output signal of the first amplifier and the output signal of the second amplifier.