Voltage Generator with Opposing Temperature Coefficients
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Solution Overview
Problem
Existing reference voltage generators face challenges in maintaining a stable output voltage across temperature variations due to the temperature-dependent characteristics of semiconductor devices, leading to complex circuits that consume high current and require significant voltage headroom.
Innovation Solution
A reference voltage generator comprising two coupled stages with opposite temperature characteristics, where the first stage includes a transistor and a resistive element, and the second stage includes a diode-connected transistor or bipolar transistor, allowing for a complementary temperature coefficient that reduces the overall temperature coefficient of the output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If temperature compensation is implemented in reference voltage generator, then output voltage stability is improved, but circuit complexity increases
Solution Approach 1:
The reference voltage generator is divided into two distinct stages: a first stage generating a first reference voltage and a second stage generating a second reference voltage. Each stage can be independently designed and optimized, allowing complex temperature compensation to be broken down into simpler, manageable segments that can be separately implemented and tuned.
Solution Approach 2:
The first stage is specifically designed to produce a first temperature coefficient that is substantially equal in magnitude but opposite in sign to the second temperature coefficient from the second stage. This preliminary anti-action approach pre-compensates for temperature variations before they affect the final output, effectively canceling out temperature drift and stabilizing the output voltage.
2Stability of the object's composition
If temperature compensation is implemented in reference voltage generator, then output voltage stability is improved, but current consumption increases
Solution Approach 1:
By segmenting the temperature compensation function into two separate stages, each stage can operate at optimized current levels. The first stage handles the positive temperature coefficient compensation while the second stage handles the negative temperature coefficient, allowing each to be efficiently designed without requiring excessive current from a single complex circuit.
Solution Approach 2:
The invention changes the temperature coefficient parameter by using transistors with different threshold voltage temperature characteristics. The first transistor is designed with a positive temperature coefficient while the second transistor has a negative temperature coefficient. By adjusting transistor dimensions, doping levels, and operating conditions, the circuit achieves temperature compensation through parameter optimization rather than high current consumption.
3Stability of the object's composition
If temperature compensation is implemented in reference voltage generator, then output voltage stability is improved, but voltage headroom requirement increases
Solution Approach 1:
Dividing the reference voltage generation into two stages allows each stage to operate within smaller voltage ranges. The first stage operates with a first voltage headroom requirement while the second stage operates with a second voltage headroom requirement, and their combined output achieves temperature stability without requiring excessive total voltage headroom compared to a single complex compensated circuit.
Solution Approach 2:
The invention optimizes voltage headroom by changing the operating parameters of the transistors, including threshold voltage selection, gate-source voltage levels, and current densities. By carefully selecting these parameters, the circuit achieves the necessary temperature compensation while maintaining operation within acceptable voltage headroom constraints for integrated circuit implementation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a self-starting reference voltage with reduced temperature coefficient, enabling a stable output voltage with low current consumption and minimal voltage headroom, suitable for integration in electronic circuits.
Implementation Method 1
the first transistor is configured to pass a current when its gate voltage is approximately the same as its source voltage
Implementation Method 2
the first stage has a voltage versus temperature characteristic of an opposite sign to a voltage versus temperature characteristic of the second stage
Data Source
AI summary
A voltage generator is provided which is reliable, self starting and only requires a few components. The voltage generator comprises a first stage that provides a current to a second stage. The first stage has a temperature coefficient of one sign, such as positive, and the second stage has an opposing temperature coefficient, e.g. negative. The responses are summed such that the overall temperature coefficient is reduced.