Amplifier Dynamic Feedback Linearization for Intermodulation Control
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Solution Overview
Problem
Amplifiers exhibit nonlinear performance above a certain input power threshold, leading to distorted output signals and reduced power efficiency, with existing solutions like pre-distortion circuits causing unwanted intermodulation distortion and requiring complex, power-consuming designs.
Innovation Solution
A method and system using dynamic feedback with a feedback path coupled to the amplifier's output and input, featuring gain control elements and a controller to apply control voltages, ensuring a constant gain factor and relative phase shift across nonlinear operating ranges, thereby preventing intermodulation distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the input signal power is increased above the threshold to improve power efficiency, then the power efficiency is improved, but the amplifier exhibits nonlinear performance causing signal distortion
Solution Approach 1:
The patent implements a feedback path that samples the output signal and feeds it back to the input through a feedback network. The feedback signal is combined with the input signal to create a linearized output. This feedback mechanism dynamically adjusts the signal to compensate for nonlinear distortions, allowing the amplifier to operate at higher power levels while maintaining signal fidelity.
2Reliability
If a pre-distortion circuit is used to correct nonlinear distortions, then the signal fidelity is improved, but unwanted intermodulation distortion byproducts are generated due to mismatches
Solution Approach 1:
Instead of using a separate pre-distortion circuit that requires precise matching, the patent uses a feedback approach where the actual output signal is sampled and fed back to correct distortions in real-time. This closed-loop system automatically adapts to the amplifier's actual nonlinear characteristics, eliminating the need for pre-characterization and reducing intermodulation distortion byproducts.
3Reliability
If a pre-distortion circuit is used to correct nonlinear distortions, then the signal fidelity is improved, but the device complexity and power consumption increase
Solution Approach 1:
The patent integrates the linearization function directly into the amplifier's feedback loop, combining the amplification and linearization functions into a single integrated structure. This eliminates the need for a separate pre-distortion circuit and its associated complexity, while the feedback network uses simple components to achieve the linearization effect.
4Reliability
If a pre-distortion circuit is used to correct nonlinear distortions, then the signal fidelity is improved, but the power consumption increases
Solution Approach 1:
By integrating the linearization function into the amplifier's existing feedback loop, the patent eliminates the need for a separate power-consuming pre-distortion circuit. The feedback network uses passive components and the amplifier's own output signal, requiring minimal additional power while achieving the same linearization effect.
Data Source
AI summary
The present disclosure describes a method and system for linearizing an amplifier using transistor-level dynamic feedback. The method and system enables nonlinear amplifiers to exhibit linear performance using one or more of gain control elements and phase shifters in the feedback path. The disclosed method and system may also allow an amplifier to act as a pre-distorter or a frequency/gain programmable amplifier.