Feedforward Cancellation Amplifier Bands for IMD Reduction
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Solution Overview
Problem
Power amplifiers with nonlinear circuitry suffer from intermodulation distortion when processing broadband signals, which reduces their linearity and efficiency.
Innovation Solution
The implementation of a feedforward cancellation amplifier circuit with a main amplifier and a feedforward cancellation amplifier, where the latter is configured to operate in narrower frequency bands within the broadband range of the main amplifier, reducing intermodulation distortion through cross-coupling and distortion subtraction, while consuming less power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a main broadband amplifier operates across a wide frequency range, then broadband signal amplification is achieved, but intermodulation distortion increases due to nonlinear circuitry
Solution Approach 1:
The broadband frequency range is divided into multiple narrower frequency bands, with each band handled by a dedicated feedforward cancellation amplifier. This segmentation allows each amplifier to be optimized for its specific band, reducing intermodulation distortion while maintaining overall broadband coverage through the combination of all bands.
Solution Approach 2:
Feedforward cancellation amplifiers are introduced as intermediary components that process signals through a feedforward path and subtract distortion components from the main amplifier output. These intermediaries actively cancel intermodulation distortion without requiring the main amplifier to operate linearly across the entire broadband range.
2Reliability
If traditional amplifier designs use high power consumption to maintain linearity, then linearity is improved, but power efficiency deteriorates
Solution Approach 1:
The system changes the operating parameters of different amplifiers across frequency bands. Feedforward cancellation amplifiers operate at lower power levels in their respective narrow bands, while the main amplifier operates efficiently across the broadband range. This parameter optimization achieves high linearity without requiring high power consumption across the entire system.
3Object-generated harmful factors
If feedforward cancellation amplifiers operate in narrower frequency bands, then intermodulation distortion is reduced in those bands, but device complexity increases
Solution Approach 1:
The feedforward cancellation amplifiers are designed with multi-functionality, handling both signal amplification and distortion cancellation within their respective frequency bands. This universal design reduces the need for separate dedicated cancellation circuits for each band, simplifying the overall device structure while maintaining effective distortion reduction.
Data Source
AI summary
A circuit includes a main amplifier having a first input and a first output. A main bias circuit is coupled to the main amplifier, and the main bias circuit configured to operate the main amplifier in a first frequency band. A feedforward cancellation amplifier has a second input and a second output, in which the second input is coupled to the first input, and the second output is coupled to the first output. A filter is coupled between the first input and the second input. A feedforward bias circuit is coupled to the feedforward cancellation amplifier. The feedforward bias circuit is configured to operate the feedforward cancellation amplifier in a second frequency band within and narrower than the first frequency band.