Spread-Spectrum Power Supply Circuit for Audio Noise Spur Reduction
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Solution Overview
Problem
Audio apparatuses operating in power-saving mode introduce noise spur into the system using pulse frequency modulation, causing discomfort due to varying power levels.
Innovation Solution
A power supplier circuit that includes a random number sequence generator, a control circuit, and a power circuit, which generates a power signal with a spread spectrum by using a random number sequence to vary the duty cycle of the control signal, thereby reducing noise and discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pulse frequency modulation is used to reduce power consumption in power-saving mode, then energy efficiency is improved, but noise spur is introduced causing discomfort to ears
Solution Approach 1:
The patent applies parameter changes by modifying the duty cycle of the power signal based on random number sequences. The control circuit adjusts the duty cycle dynamically, spreading the power spectrum across multiple frequencies rather than concentrating it at a single frequency, thereby reducing audible noise while maintaining power efficiency
Solution Approach 2:
The patent implements dynamics by making the duty cycle variable rather than fixed. The control circuit continuously adjusts the duty cycle according to random number sequences, creating a dynamic power signal that adapts its characteristics to minimize noise perception while maintaining energy efficiency
2Object-affected harmful factors
If duty cycle is varied using random number sequence to spread spectrum, then noise spur is reduced, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the control function into separate modules: a random number sequence generator circuit, a control circuit, and a power circuit. This modular approach allows each component to perform a specific function, making the overall system manageable despite the increased complexity required for spread spectrum operation
3Object-affected harmful factors
If power signal is spread across larger frequency range, then noise discomfort is reduced, but power signal stability varies
Solution Approach 1:
The patent implements feedback by having the control circuit continuously monitor and adjust the duty cycle based on random number sequences. This feedback mechanism ensures that the power signal maintains its intended spread spectrum characteristics while compensating for any variations, thereby balancing noise reduction with signal stability
Data Source
AI summary
A power supplier circuit supplies a power signal to a codec of an audio apparatus. The power supplier circuit includes a random sequence generation circuit, a control circuit, and a power circuit. The random sequence generation circuit generates a random sequence. The control circuit outputs a first control signal according to the random sequence, a first reference signal, and the power signal. The power circuit generates the power signal according to the first control signal, such that the power signal is spread in response to the random sequence.