Pulse Width Filtering Circuit for Glitch Rejection and Timing Preservation
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Solution Overview
Problem
Electronic circuits face issues with small pulse width signals, known as glitches, which can negatively impact circuit operation and performance, and existing technologies have not effectively filtered or regulated these signals to prevent their propagation.
Innovation Solution
A pulse width filtering circuit comprising an input transition detection circuit and a delay circuit that filters out pulses shorter than a predetermined time by using separate delay circuits for rising and falling edges, with a switching circuit to selectively output the filtered signals, thereby maintaining the timing properties of the original input signal and improving noise immunity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pulse width filtering circuit uses separate delay circuits for rising and falling edges, then the reliability of filtering is improved, but the device complexity increases
Solution Approach 1:
The pulse width filtering circuit is segmented into separate delay circuits for rising edges and falling edges. Each delay circuit independently processes one type of transition, allowing precise control over pulse width filtering for each edge type. This segmentation improves reliability by enabling independent optimization of filtering parameters for rising and falling edges without interfering with each other.
2Object-affected harmful factors
If the delay circuit filters out short pulses, then noise immunity is improved, but the timing properties of the original signal may be affected
Solution Approach 1:
The delay circuits are configured with specific delay times that are locally optimized to match the characteristics of legitimate signal transitions. By setting the delay time to be slightly longer than the pulse width of valid signals but shorter than the duration of noise glitches, the circuit achieves local quality differentiation between useful signals and noise, filtering out short pulses while preserving timing properties of valid transitions.
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 solution effectively filters out short signal pulses, preserving the timing properties of the input signal and enhancing noise immunity, ensuring reliable circuit operation by preventing short pulses from affecting the output.
Implementation Method 1
the first delay circuit comprises a first capacitor, a charging time of which determines the first predetermined period
Data Source
AI summary
A pulse width filtering circuit for filtering pulse signals includes an input transition detection circuit detecting change of state of an input signal, including a first transition from a low signal to a high signal and a second transition from the high signal to the low signal; a first delay circuit determining whether the high signal from the first transition is maintained longer than a first period and, if so, generating a first output indicative of the first transition, after the first period; a second delay circuit determining whether the low signal from the second transition is maintained for longer than a second period and, if so, generating a second output indicative of the second transition, after the second period; and a switching circuit connected to the first and second delay circuits and selectively outputting the first output and the second output, based on the state of the input signal.