Temperature-to-Digital Converter Using Nonlinearity Cancellation
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Solution Overview
Problem
Conventional temperature sensors have a limited operational range due to transistor model dependency, requiring complex designs and explicit data converters for accurate temperature sensing across a wide range.
Innovation Solution
A temperature-to-digital converter design that cancels and matches temperature non-linearity of different blocks, integrating digitization into the sensing unit and using a feedback loop, independent of transistor models, to operate from −55° C. to 200° C. with a resolution of 2° C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional temperature sensors use transistor model dependency for temperature sensing, then the sensor can operate with simple design, but the operational temperature range is limited
Solution Approach 1:
The patent changes the operating parameters by using multiple transistor models (weak inversion, moderate inversion, strong inversion) across different temperature ranges. Each transistor model is optimized for specific temperature conditions, allowing the sensor to maintain accuracy across a wide temperature range from -55°C to 200°C without increasing design complexity
Solution Approach 2:
The patent dynamically switches between different transistor models based on temperature conditions. The system adapts its operating mode by selecting appropriate transistor inversion regions, enabling the sensor to respond effectively to varying temperature conditions while maintaining a relatively simple overall design structure
2Adaptability or versatility
If explicit data converters and additional circuits are added to extend temperature range, then the operational temperature range is improved, but the device complexity increases
Solution Approach 1:
The patent merges the temperature sensing function with the digitization function into a single integrated circuit. By combining these functions and using transistor models that operate across wide temperature ranges, the patent eliminates the need for separate explicit data converters and additional compensation circuits, thereby extending the operational temperature range while maintaining design simplicity
Solution Approach 2:
The patent employs universal transistor models that can function across multiple temperature ranges and inversion regions. These multi-functional transistor models serve both as temperature sensing elements and as signal conditioning elements, eliminating the need for dedicated compensation circuits and data converters for each temperature range
3Measurement precision
If high precision ADC is used to maintain accuracy across temperature range, then the measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent changes the approach to maintaining precision by using transistor models with predictable parameter variations across temperature. Instead of relying on high-precision ADCs, the patent uses the inherent temperature characteristics of transistors in different inversion regions to maintain measurement accuracy, thereby reducing ADC complexity and overall system cost
Data Source
AI summary
The present disclosure relates to a temperature-to-digital converter that fulfills the requirement of sensing temperature in applications, such as automotive, where operation in a wide temperature range is essential. Due to the dependency of the transistor models on the temperature, the conventional temperature sensors have a limited range in which they have an acceptable function. The disclosed sensor overcomes this problem by introducing a design independent of the transistor model and relies on cancelling and matching temperature non-linearity of different blocks. The approach according to the present disclosure enables the design of a temperature sensor that is operational in the never before achieved range of −55° C. to 200° C.