Compensated Hysteresis Circuit for Stable Switch Points
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Solution Overview
Problem
Hysteresis circuits face challenges in maintaining precision due to variations in temperature and power supply voltage, which affect their performance in applications like level detectors and oscillators.
Innovation Solution
A compensated hysteresis circuit is designed with a temperature and voltage compensator circuit that adjusts the switch points and differential between them, using P-channel and N-channel transistors and an inverter to provide self-biasing threshold control and trim transistors for optimal compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hysteresis circuits are used, then the circuit can provide hysteresis functionality for level detection and oscillation, but the switch points vary due to temperature and power supply voltage changes, reducing precision
Solution Approach 1:
The patent implements a feedback mechanism where the output of the hysteresis circuit is fed back through a compensation network to the set terminals. This feedback loop continuously adjusts the switch points to counteract variations caused by temperature and voltage changes, thereby maintaining precision without sacrificing hysteresis functionality
Solution Approach 2:
The patent dynamically changes the electrical parameters (voltage levels) at the set terminals based on detected variations in temperature and power supply voltage. By adjusting these parameters in real-time through the compensation circuit, the circuit maintains stable switch points despite environmental changes
2Device complexity
If the set terminals are connected to power supply terminals, then the circuit structure is simple, but the switch points are directly affected by power supply voltage variations
Solution Approach 1:
The patent introduces a compensation network as an intermediary between the power supply and the set terminals. This intermediary circuit buffers the set terminals from direct power supply variations while still allowing simple connection topology, thereby protecting switch point precision without significantly increasing structural complexity
3Measurement precision
If compensation circuits are added to reduce variations, then precision is improved, but the device complexity increases
Solution Approach 1:
The compensation circuit is designed to perform multiple functions simultaneously: it compensates for temperature variations, compensates for power supply voltage variations, and maintains the hysteresis functionality. By making the compensation circuit multi-functional, the patent reduces the need for separate compensation circuits for each parameter, thereby limiting the increase in overall device complexity
Data Source
AI summary
A compensated hysteresis circuit comprises a hysteresis circuit including an output node and a first control transistor. The first control transistor provides feedback to the hysteresis circuit. A temperature and voltage compensation circuit includes a self-biasing threshold control circuit including an input coupled to the output node of the hysteresis circuit, and a first trim transistor coupled between the first control transistor of the hysteresis circuit and the self-biasing threshold control circuit.