Switched-Mode Amplifier Double Sampling for Carrier Ripple Attenuation
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Solution Overview
Problem
Conventional switched-mode amplifiers face limitations in achieving improved harmonic distortion performance and high attenuation of residual unwanted ripple signals without compromising stability margins or requiring complex high-order filters.
Innovation Solution
The implementation of a switched-mode amplifier architecture that includes a loop filter, a pre-modulation block for uniform pulse-width modulation, and double sampling by the pre-modulation block in conjunction with the PWM block, which attenuates residual clock signals using transmission zero notches, eliminating the need for an output filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high-order filters are employed to provide additional attenuation of the carrier signal, then the attenuation of residual carrier signals is improved, but the complexity of the system increases and stability margins are reduced
Solution Approach 1:
The filtering function is segmented into two parts: the loop filter handles in-band signal processing, while the uniform pulse-width modulation technique handles carrier frequency attenuation. This segmentation eliminates the need for high-order output filters while maintaining effective carrier signal attenuation through the pre-modulation block's transmission zero notches.
Solution Approach 2:
The pre-modulation block acts as an intermediary between the loop filter and the PWM block. It introduces transmission zero notches at carrier frequencies that attenuate residual carrier signals before they reach the output, serving as a mediator that provides filtering functionality without requiring complex high-order output filters.
2Manufacturing precision
If high in-band open loop gain is achieved, then distortion and noise performance are improved, but the attenuation of PWM carrier frequency is reduced
Solution Approach 1:
The system segments the filtering responsibilities: the loop filter provides high in-band open loop gain for improved distortion and noise performance, while the pre-modulation block provides carrier frequency attenuation through transmission zero notches. This segmentation allows both high in-band gain and high carrier frequency attenuation to coexist without trade-off.
Solution Approach 2:
The system applies different quality characteristics to different frequency ranges: high gain in the in-band audio range for low distortion, and deep notches at carrier frequencies for high attenuation. The pre-modulation block introduces frequency-selective characteristics that provide local quality optimization at carrier frequencies while preserving in-band performance.
3Device complexity
If filter-less architecture is used, then the complexity is reduced and efficiency is improved, but the attenuation of unwanted high-frequency components is compromised
Solution Approach 1:
The pre-modulation block serves as an intermediary that provides the necessary high-frequency attenuation functionality within the filter-less architecture. By introducing transmission zero notches at carrier frequencies, it acts as a mediator that enables effective attenuation of unwanted high-frequency components without requiring a separate output filter stage.
Solution Approach 2:
The system changes the parameter of the PWM modulation by introducing uniform pulse-width modulation with pre-modulation. This parameter change creates transmission zero notches at carrier frequencies that provide high-frequency attenuation, enabling the system to achieve effective filtering without the physical filter components that would increase complexity.
Data Source
AI summary
Systems and methods for switched-mode amplifiers having improved harmonic distortion are disclosed. High order in-band filtering is enabled without undue trade-off of distortion due to intermodulation/aliasing. A pre-modulation block is introduced, deployed between a loop filter block and a pulse-width modulation block, performing uniform pulse-width modulation. The pre-modulation block attenuates/removes amplitude dependent high frequency ripples before pulse-width modulation. The pre-modulation block in conjunction with the pulse-width modulation block performs double sampling of the input signals.