Schmitt Trigger Input Circuit for Ground Noise Chatter Suppression
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Solution Overview
Problem
Parasitic characteristics of bond wires and lead pins in integrated circuits can cause glitches and chatter in signals due to noise on the ground plane, leading to misinterpretation of signals and adverse effects on circuit operation.
Innovation Solution
A circuit configuration that includes a Schmitt trigger, a chatter suppression circuit, a logic circuit, and a driver, which monitors changes in voltage at pads and ignores changes attributed to noise on the ground plane, thereby suppressing glitches and chatter in output signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bond wires and lead pins are used to couple pads to external components, then electrical connection is achieved, but parasitic characteristics cause signal glitches and chatter
Solution Approach 1:
A chatter suppression circuit is introduced as an intermediary component between the noisy signal source (bond wires/lead pins) and the load. This circuit actively detects and suppresses glitch signals before they propagate further, effectively mediating the harmful interaction between parasitic elements and signal integrity.
Solution Approach 2:
The chatter suppression circuit employs feedback mechanisms to continuously monitor signal conditions and dynamically adjust its suppression action. By detecting the presence of glitches and chatter in real-time, the circuit provides negative feedback to counteract these disturbances, thereby improving signal reliability despite the inherent parasitic characteristics of bond wires and lead pins.
2Productivity
If ground plane noise is present, then circuit operation continues, but signal misinterpretation occurs
Solution Approach 1:
The chatter suppression circuit converts the harmful effect of ground plane noise into a detectable signal characteristic. By designing the circuit to specifically recognize glitch patterns caused by ground noise, the harmful noise becomes a trigger for the suppression mechanism, transforming the problem into a controlled response that prevents signal misinterpretation while maintaining circuit operation.
3Measurement precision
If noise-induced voltage changes are detected, then signal accuracy improves, but false triggering may occur
Solution Approach 1:
The chatter suppression circuit employs dynamic threshold adjustment and adaptive detection mechanisms rather than fixed thresholds. The circuit's response characteristics change based on the detected signal conditions, allowing it to distinguish between genuine signal transitions and noise-induced false triggers. This dynamic behavior enables accurate voltage change detection while minimizing false triggering through context-aware decision-making.
Data Source
AI summary
In some examples, a circuit includes a capacitor having a first terminal and a second terminal, the first terminal coupled to a voltage supply terminal of the circuit. The circuit also includes a transistor having a transistor gate, a transistor drain, and a transistor source, the transistor source coupled to ground and the transistor drain coupled to an input terminal of the circuit. The transistor is configured to conduct responsive to a gate signal received at the transistor gate, the gate signal based on a signal provided at the second terminal of the capacitor. The circuit also includes a Schmitt trigger having a Schmitt trigger input coupled to the transistor drain.