Power Amplifier Linearization Feedback System
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Solution Overview
Problem
Power amplifiers face challenges in maintaining linearity due to the generation of non-linear intermodulation products and unwanted spectral components, which degrade performance and increase power consumption.
Innovation Solution
A system with a linearizer that includes inner and outer signal cancellers, couplers, and attenuators to process and compensate for intermodulation products by generating a compensation signal that reduces the amplitude of non-linear components, improving the linearity of the power amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power amplifiers operate at high power levels, then output power is improved, but non-linearity components such as intermodulation products increase and degrade performance
Solution Approach 1:
The patent captures the harmful intermodulation products generated by the power amplifier and redirects them through a feedback path where they are inverted and re-injected into the amplifier input. This converts the harmful non-linearity into a beneficial canceling signal, reducing the intermodulation products while maintaining high output power operation
Solution Approach 2:
The patent implements a feedback mechanism where output signal samples are taken from the power amplifier, processed through signal cancellers to extract intermodulation components, inverted, and fed back to the input. This closed-loop feedback system continuously reduces non-linearity effects, enabling high power operation with improved linearity performance
2Manufacturing precision
If existing linearization techniques are applied, then linearity is improved, but device complexity increases significantly
Solution Approach 1:
The patent makes the output signal samples serve multiple functions: they are used both for monitoring amplifier performance and as the source signal for generating the feedback cancellation signal. This multi-functionality reduces the need for separate signal paths and components, simplifying the overall system while achieving effective linearization
Solution Approach 2:
The patent introduces signal cancellers as intermediary components that selectively extract and process specific intermodulation frequency components from the feedback path. These intermediaries enable precise targeting of harmful frequencies without requiring complex processing of the entire signal spectrum, reducing overall system complexity
3Manufacturing precision
If feedback loops are added to reduce non-linearity, then ACPR is improved, but power consumption increases
Solution Approach 1:
The patent applies feedback cancellation selectively only to the specific intermodulation frequency components that cause ACPR degradation, rather than attempting to linearize the entire output spectrum. This partial action approach targets only the harmful frequencies with minimal processing, reducing the power consumption of the feedback system while achieving ACPR improvement
Data Source
AI summary
Linearizers can improve the linearity of power amplifiers by canceling or reducing amplitude of non-linearity components, (e.g., IM3, IM5, IM7, IM9, etc.) generated by the power amplifier. The linearizers can obtain samples of signals output by the power amplifier and process the samples to produce a compensation signal that is applied onto or into a transmission path leading to the power amplifier's input. The compensation signal is generated such that when amplified by the power amplifier, the amplified compensation signal cancels or reduces at least a portion of the non-linearity components produced by the power amplifier. A controller can improve the correction of the non-linearity components by executing one or more calibration algorithms and/or one or more tuning algorithms and adjusting settings of the linearizer based on the results of the algorithm(s).