Selectable Schmitt Trigger Hysteresis Across Multiple Supply Voltages
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Solution Overview
Problem
Schmitt trigger circuits optimized for one power supply potential often fail to meet requirements for another potential, as they struggle to maintain a large threshold difference while keeping thresholds within a specific range, leading to suboptimal performance across different power supply magnitudes.
Innovation Solution
The Schmitt trigger circuit dynamically adjusts its operation based on a selection signal associated with the power supply potential, enabling or disabling shunt circuits to selectively activate current paths, allowing independent optimization for high-voltage and low-voltage modes, thus ensuring a large threshold difference and compliance with standards for both modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the Schmitt trigger circuit is optimized for one power supply potential, then the threshold difference and threshold range requirements are met for that potential, but the circuit fails to meet requirements when operated at another power supply potential
Solution Approach 1:
The patent implements dynamic adaptability by providing two separate Schmitt trigger circuits (first and second Schmitt trigger circuits) that can be selectively activated based on the power supply potential. A selection signal determines which circuit is active, allowing the system to dynamically adjust its operation mode to match the power supply conditions, thereby maintaining reliable threshold performance across different potentials
Solution Approach 2:
The patent divides the Schmitt trigger functionality into separate segments (first Schmitt trigger circuit for high-voltage mode, second Schmitt trigger circuit for low-voltage mode). Each segment is independently optimized for its specific power supply potential, and a selection mechanism chooses the appropriate segment based on operating conditions, resolving the contradiction between adaptability and reliability
2Reliability
If the threshold difference is made large, then the hysteresis characteristic is improved, but the thresholds may fall outside the required range for certain power supply potentials
Solution Approach 1:
The patent applies local quality by designing different threshold characteristics for different operating modes. The first Schmitt trigger circuit has thresholds optimized for high-voltage operation (VDD1), while the second circuit has thresholds optimized for low-voltage operation (VDD2). Each circuit maintains large threshold differences appropriate for its specific power supply potential, ensuring both hysteresis performance and threshold range compliance without compromise
Data Source
AI summary
A Schmitt trigger circuit includes a first circuit; a second circuit; a first switch; a third circuit; and a second switch. The first circuit output the output signal of a second or first logical level. The second circuit is coupled to a first potential node at a first end, and sends a current between the first end and a second end based on the output signal. The first switch electrically couples or uncouples the second end and a first node based on a selection signal. The third circuit is coupled to a second potential node at a third end, and sends a current exclusively with the second circuit between the third end and a fourth end based on the output signal. The second switch electrically couples or uncouples the fourth end and the first node based on the selection signal.