Oscillator Temperature Sensor With Linear Output Across Wide Ranges
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Solution Overview
Problem
There is a need for a temperature sensor that provides a substantially linear signal over an extended temperature range from −40° C. to 250° C., while being compact and having low consumption, and can be integrated with other electronic circuits.
Innovation Solution
A temperature sensor design incorporating a controllable current source, an oscillator, and a control circuit that adjusts the equivalent resistance of the oscillator to maintain a constant oscillation frequency, using MOS transistors and resistors with temperature-dependent coefficients to ensure linear signal variation with temperature, along with an analog-digital converter and follower circuit for signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature sensors are used to achieve linear signal output over extended temperature range, then measurement accuracy is improved, but device complexity and calibration requirements increase
Solution Approach 1:
The patent changes the operating parameters of the oscillator by dynamically adjusting its equivalent resistance through a controllable current source. This allows the oscillator to maintain constant frequency despite temperature variations, achieving linear temperature measurement without complex calibration procedures
Solution Approach 2:
The control circuit continuously monitors the oscillator's equivalent resistance and adjusts the controllable current source to maintain the resistance at a reference value. This feedback mechanism ensures stable oscillation frequency and linear temperature signal output across the extended temperature range
2Measurement precision
If high precision temperature sensors are implemented, then measurement accuracy is improved, but power consumption increases
Solution Approach 1:
The patent uses an oscillator that operates in periodic cycles to generate temperature measurement signals. This periodic operation allows the system to achieve accurate measurements while consuming minimal power compared to continuous high-precision sensing methods
Solution Approach 2:
The oscillator inherently provides the measurement signal through its natural oscillation, and the control circuit automatically adjusts parameters to maintain accuracy. This self-regulating system reduces the need for additional power-hungry signal conditioning circuits
3Volume of moving object
If compact temperature sensors are designed, then device size is reduced, but integration with electronic circuits becomes more difficult
Solution Approach 1:
The patent merges the temperature sensing function with standard electronic circuit components, particularly the oscillator and controllable current source. This integration allows the temperature sensor to be manufactured using standard semiconductor processes, facilitating easy incorporation into electronic circuits without increasing overall device size
Solution Approach 2:
The oscillator circuit serves multiple functions: it generates the measurement signal, provides frequency reference, and enables temperature compensation through its controllable resistance. This multi-functionality reduces the need for separate dedicated components, enabling compact design with easy integration
Data Source
AI summary
A temperature sensor supplying a measurement signal varying linearly to within 10% as a function of the temperature at least over a temperature range, including an oscillator supplied by a supply voltage and supplying a first oscillating signal, said oscillator including first MOS transistors, the voltage at each internal node of the oscillator having a dynamic range equal to the supply voltage, the measuring signal corresponding to the supply voltage.