Programmable Hysteresis Deglitcher for High-Rate Signal Filtering
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Solution Overview
Problem
Conventional deglitching circuitry requires increasing resources and becomes space-consuming and expensive as sampling intervals increase, necessitating a solution that can operate at high sampling rates while reducing resource usage.
Innovation Solution
A deglitcher circuit with programmable hysteresis that counts samples of changed states and decrements samples of original states, using a register to determine when to change the output signal state, thereby reducing the number of memory elements required and allowing for more samples without increasing memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional deglitching circuitry uses a chain of flip-flops to sample input signals at fixed time intervals, then the input signal can be filtered for glitches, but the number of memory elements (flip-flops) required increases linearly with the sampling interval, making the circuit increasingly space-consuming and expensive
Solution Approach 1:
The patent implements a dynamic sampling approach where a single flip-flop is reused across multiple sampling intervals through a counter-controlled mechanism. Instead of using a fixed chain of flip-flops, the system dynamically reuses the same memory element by resetting and reusing it after each sampling period, controlled by a counter that tracks the number of samples taken. This dynamic reuse reduces the static memory requirement from N flip-flops to just 1 flip-flop plus a counter.
Solution Approach 2:
The patent applies the discarding and recovering principle by resetting the flip-flop after each sampling interval and reusing it for the next sample. The counter tracks how many samples have been taken and resets the flip-flop when the sampling interval is complete, allowing the same memory element to be recovered and reused indefinitely. This eliminates the need to permanently allocate N flip-flops for N sampling intervals.
2Productivity
If the sampling interval is increased to reduce sampling rate and resource usage, then fewer memory elements are needed, but the ability to accurately reconstruct high-frequency input signals is compromised
Solution Approach 1:
The patent incorporates feedback through a counter that monitors the number of samples taken and controls the reset timing of the flip-flop. The counter provides feedback about the sampling state, enabling the system to maintain the correct sampling interval dynamically. This feedback mechanism ensures that even with a single reused flip-flop, the sampling rate and timing remain accurate for high-frequency signal reconstruction.
Solution Approach 2:
The patent implements periodic action by using a counter to control the periodic resetting of the flip-flop at appropriate intervals. The counter increments with each clock cycle and triggers a reset after a predetermined number of samples, creating a periodic sampling pattern that maintains accuracy for high-frequency signals while reusing the same memory element. This periodic control enables high sampling rates without requiring proportionally more memory elements.
Data Source
AI summary
Disclosed is a deglitcher circuit having a programmable hysteresis. The deglitcher samples a received input signal, wherein the input signal may include one or more glitches. Responsive to a change in state of the sampled input signal, the deglitcher counts the number of samples of the changed state of the input signal. The count value increments with each sampled changed state, and decrements with each sampled original state of the input signal. When the count value reaches a threshold, the state of the output signal is changed. The output signal of the disclosed deglitcher circuit provides an accurate, glitch-free reconstruction of the sampled input signal. Additionally, the disclosed deglitcher circuit reduces the number of memory elements required for a given number of samples of the input signal, thereby allowing for a larger number of samples to be taken without necessarily having to increase the memory elements required by the deglitcher.