Temperature Compensation Circuit for MOS Transistor Threshold Stability
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Solution Overview
Problem
Conventional metal oxide semiconductor (MOS) transistors experience a variation in threshold voltage with temperature changes, making it challenging to maintain a stable threshold voltage across different temperature ranges, which is a requirement for certain applications.
Innovation Solution
A temperature compensation circuit is introduced, featuring a voltage generator that provides a voltage proportional to absolute temperature (VPTAT) to drive the body of the MOS transistor, thereby compensating for threshold voltage variations due to temperature changes, ensuring a temperature-invariant equivalent threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MOS transistor is used without temperature compensation, then the device structure is simple, but the threshold voltage varies with temperature changes
Solution Approach 1:
A voltage generator circuit is introduced as an intermediary component to produce a body-source voltage that compensates for temperature-induced threshold voltage variations. This mediator circuit generates a compensation voltage proportional to temperature changes and applies it to the body terminal of the MOS transistor, thereby stabilizing the threshold voltage without fundamentally altering the transistor structure.
Solution Approach 2:
The invention changes the body-source voltage parameter dynamically based on temperature conditions. By adjusting the body-source voltage to counteract temperature effects, the threshold voltage is kept stable. The voltage generator modifies this voltage parameter in response to temperature changes, ensuring the equivalent threshold voltage remains constant across different operating temperatures.
2Reliability
If a voltage generator is added to compensate threshold voltage, then temperature invariance is achieved, but the circuit complexity increases
Solution Approach 1:
The voltage generator is designed to automatically sense temperature changes and generate the appropriate compensation voltage without requiring external control circuits or additional complex components. The circuit self-regulates by using the temperature-dependent characteristics of its internal components to produce the correct body-source voltage, thereby achieving temperature compensation with minimal added complexity.
Data Source
AI summary
A temperature compensation circuit, applied on a metal oxide semiconductor (MOS) transistor, with a threshold voltage varying with respect to a temperature value of the MOS transistor, for having the MOS transistor corresponding to an equivalent threshold voltage substantially with a constant value throughout a temperature range, comprises a voltage generator. The voltage generator provides a voltage proportional to absolute temperature (VPTAT) to drive the body of the MOS transistor in such way that a variation of the threshold voltage due to temperature variation of the MOS transistor is substantially compensated with a variation of the threshold voltage due to body-source voltage variation of the MOS transistor, so that the MOS transistor corresponds to the equivalent threshold voltage that is temperature invariant.