Nested Feedback Class-D Amplifier for Wider Stable Bandwidth
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Solution Overview
Problem
Class-D amplifiers face limitations in gain and bandwidth due to stability issues, which restrict their performance in producing output signals with acceptable distortion and power levels over typical audio frequency ranges.
Innovation Solution
The implementation of nested feedback loops within class-D amplifiers, comprising a first and second feedback loop, with additional modules such as integrator and compensator modules, enhances error correction and stability, allowing for greater gain and bandwidth without introducing unwanted distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback is used to reduce distortion and noise, then output signal quality is improved, but gain and bandwidth are limited due to stability issues
Solution Approach 1:
The feedback system is segmented into multiple independent loops (inner feedback loop and outer feedback loop), each handling different aspects of signal correction. The inner loop focuses on immediate distortion reduction while the outer loop manages overall stability and bandwidth, allowing the system to achieve both high signal quality and extended gain bandwidth without compromising stability
Solution Approach 2:
The feedback loops are nested with the inner feedback loop contained within the outer feedback loop structure. This nested configuration allows the inner loop to correct high-frequency distortions rapidly while the outer loop provides broader bandwidth control and stability, enabling the system to overcome the traditional trade-off between signal quality and gain bandwidth
2Power
If gain is increased to achieve higher power output, then amplifier power is improved, but stability issues arise causing distortion
Solution Approach 1:
The amplifier employs dynamic feedback adjustment where the inner and outer loops operate at different speeds and gain levels. The inner loop provides rapid response to maintain stability during high-power output, while the outer loop dynamically adjusts overall system parameters to prevent distortion, enabling the amplifier to deliver high power while maintaining stability across varying operating conditions
Data Source
AI summary
A class-D amplifier with multiple “nested” levels of feedback. The class-D amplifier surrounds an inner feedback loop, which takes the output of a switching amplifier and corrects for errors generated across the switching amplifier, with additional feedback loops that also take the output of the switching amplifier.