Pulse Width Filter Circuit for Distortion-Free Cut-Off Detection
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Solution Overview
Problem
Pulse width filters using RC circuits often distort input signals when their pulse width is slightly more than the cut-off pulse, due to unequal increasing and decreasing delay periods, leading to incorrect signal transmission.
Innovation Solution
A pulse width filter design that includes an increasing circuit, a decreasing circuit, and a controller to generate a modulation signal synchronized with the input signal edges, determining whether the pulse width exceeds a cut-off pulse width, and adjusting the signal transmission accordingly to prevent distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an RC filter is used to implement a pulse width filter, then the circuit structure is simple, but the input signal is distorted when the pulse width is slightly more than the cut-off pulse due to unequal increasing and decreasing delay periods
Solution Approach 1:
The filter unit is divided into separate increasing circuit and decreasing circuit modules, each handling one edge type. This segmentation allows independent optimization of charging and discharging paths to achieve equal delay periods while maintaining overall circuit simplicity
Solution Approach 2:
The patent inverts the traditional RC filter approach by using active circuits that can precisely control both increasing and decreasing edges. Instead of relying on passive RC time constants that create unequal delays, the invention uses active switching elements to symmetrize the delay periods, resolving the distortion issue
2Productivity
If the pulse width of the input signal is slightly more than the cut-off pulse, then the signal should be transmitted, but the signal is distorted due to unequal delay periods in the RC filter
Solution Approach 1:
The output signal is fed back to the filter unit to control the switching elements. This feedback mechanism ensures that the modulation signal accurately reflects the input signal's pulse width, enabling precise control of signal transmission while maintaining signal integrity by compensating for delay period differences
Solution Approach 2:
The patent changes the operational parameters of the filtering process by using controllable switching elements that can adjust their resistance and capacitance characteristics dynamically. This allows the increasing and decreasing delay periods to be equalized, ensuring accurate signal transmission without distortion
Data Source
AI summary
The present invention relates a pulse width filter generating a modulation signal that is increased in synchronization with one of an increasing edge and a decreasing edge of the input signal and is decreased in synchronization with the other of the increasing edge and the decreasing edge, and transmitting the input signal of the modulation signal. The input signal passed through the filter unit is inverted thereby being an output signal. The pulse width filter controls the increasing and the decreasing of the modulation signal according to the output signal and the input signal passed through the filter unit, and the modulation signal is a signal to determined whether the pulse width of the input signal is more than the predetermined cut-off pulse width.