PWM Noise Inversion Circuit for Active Signal Noise Reduction
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Solution Overview
Problem
Existing devices such as headphones and vehicle suspension systems require effective noise reduction mechanisms to enhance signal quality and stability, but current technologies lack efficient active noise reduction solutions.
Innovation Solution
A noise reduction signal generator comprising a comparator, conversion circuit, and low pass filter circuit that generates a noise inversion signal by comparing an input signal with a reference signal, converting the comparison result into a pulse width modulation (PWM) signal, and filtering it to produce a noise reduction signal, thereby actively reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If active noise reduction mechanisms are added to devices, then noise reduction capability is improved, but device complexity increases
Solution Approach 1:
The noise reduction function is segmented into distinct functional modules: comparator for signal comparison, conversion circuit for PWM generation, and low pass filter for noise elimination. This modular segmentation allows the complex noise reduction task to be divided into manageable stages, improving overall system organization and maintainability while achieving effective noise reduction.
Solution Approach 2:
The patent introduces PWM signals as an intermediary representation between the input signal and the final noise reduction output. The comparator generates PWM signals based on signal comparison, which then pass through the low pass filter to produce the reduced noise output. This intermediary PWM stage facilitates the noise reduction process by providing a structured intermediate form that is easier to filter.
2Measurement precision
If noise reduction processing is applied to signals, then signal quality is improved, but processing time increases
Solution Approach 1:
The conversion circuit generates periodic PWM signals with fixed duty cycles based on the comparator output. This periodic action allows the noise reduction system to process signals in regular intervals rather than continuously, reducing overall processing time while maintaining signal quality through systematic filtering at each period.
Solution Approach 2:
The patent replaces complex analog noise filtering mechanisms with a digital-like PWM conversion and filtering approach. By converting the analog comparison result into PWM signals and then using a low pass filter, the system achieves efficient noise reduction without requiring complex real-time analog processing, thereby reducing processing time while improving signal quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The noise reduction signal generator effectively reduces noise in input signals, providing an active noise reduction mechanism that improves signal quality and stability in devices equipped with it.
Implementation Method 1
The low pass filter circuit is coupled to the conversion circuit and configured to perform a filtering operation on the second PWM signal to generate a noise inversion signal
Data Source
AI summary
A noise reduction signal generator is provided. The noise reduction signal generator includes a comparator, a conversion circuit, and a low pass filter circuit. The comparator receives an input signal and a reference signal and compares the input signal and the reference signal to generate a first pulse width modulation (PWM) signal. A pulse width of the first PWM signal is correlated to a comparison result between a signal intensity of the input signal and a signal intensity of the reference signal. The conversion circuit converts the first PWM signal to a second PWM signal. A phase of the second PWM signal is different from a phase of the first PWM signal. The low pass filter circuit performs a filtering operation on the second PWM signal to generate a noise inversion signal. The noise inversion signal is configured to reduce noise of the input signal.