Switching Amplifier Feedback Loop for Stable Analog and Digital PWM
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Solution Overview
Problem
Class D amplifiers face challenges in handling both analog and digital PWM inputs while maintaining high performance and stability, especially in the presence of power supply noise and nonlinearities, requiring a feedback system with high loop gain across the audio band.
Innovation Solution
A switching amplifier system with a high-order error feedback loop using combinatorial logic and analog comparators, capable of generating a reset signal to correct errors and handle saturation events, and incorporating a digital clock for modulating pulse width modulation signals to achieve high efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a feedback loop is implemented to correct errors in the amplified output signal, then the performance and stability of the switching amplifier is improved, but the complexity of the system increases due to the need for high-order transfer functions and additional circuit components
Solution Approach 1:
The patent implements a feedback loop that feeds back a portion of the amplified output signal to the input, comparing it with the original input signal to generate an error signal. This error signal is then processed through a high-order transfer function to correct nonlinearities and distortions in the output, thereby improving reliability and stability while managing system complexity through structured feedback architecture.
2Reliability
If a high-order transfer function is used in the feedback signal to achieve high loop gain over the audio band, then the performance is improved, but the device complexity increases due to the need for multiple op-amp circuits
Solution Approach 1:
The high-order transfer function is segmented into multiple operational amplifier circuits, each handling a specific portion of the error correction task. This segmentation allows the complex high-order function to be implemented using standard op-amp building blocks, improving performance through high loop gain while managing circuit complexity through modular decomposition of the transfer function into manageable stages.
3Adaptability or versatility
If the switching amplifier handles both analog and digital PWM inputs, then the adaptability is improved, but the difficulty of detecting and measuring errors increases due to the different signal types
Solution Approach 1:
The feedback loop and error detection circuitry are designed to be universal, handling both analog and digital PWM input signals through the same architecture. The system uses a unified approach where the feedback signal is compared with the input signal regardless of its type, and the high-order transfer function processes error signals from both analog and digital sources, thereby achieving adaptability without significantly increasing error detection difficulty.
Data Source
AI summary
A switching amplifier system with a power supply, a pulse modulator configured to modulate an input signal into a pulse width modulation signal, a switching stage configured to generate an amplified output signal, and an error feedback signal configured to correct errors in the amplified output signal, where the input signal is comprised of at least one of an analog signal and a digital signal. A method of signal amplification comprising generating, by a pulse width modulator, a pulse width modulation signal, combining, by a switching stage, the input signal and the pulse width modulation signal to form an amplified output signal, and generating, by the switching stage, an error feedback signal, where the error feedback signal is configured to correct errors in the amplified output signal, and where the input signal is comprised of at least one of an analog signal and a digital signal.