PTAT Temperature Protection Circuit With Offset-Cancelled Sensing
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Solution Overview
Problem
Existing temperature protection circuits for devices, such as integrated circuits, face limitations in accuracy and require complex calibration processes, which are costly and inefficient, especially when ensuring uniform temperature across multiple devices and maintaining precision over the device's lifetime.
Innovation Solution
A circuit utilizing a Proportional-To-Absolute-Temperature (PTAT) voltage generator with offset cancellation in a first clock phase and comparator evaluation in a second clock phase, eliminating the need for separate calibration and reducing error contributions from operational transconductance amplifiers and comparators, thereby enhancing accuracy and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is performed in manufacturing environment using measurement of at least two precise temperature points, then temperature measurement accuracy is improved, but calibration time increases and manufacturing cost increases
Solution Approach 1:
The patent applies preliminary action by pre-calibrating the temperature sensor using a known temperature reference (such as a bandgap reference voltage that has a predictable temperature coefficient) during manufacturing. This preliminary calibration establishes baseline parameters that are stored in memory, eliminating the need for time-consuming multi-point calibration in the manufacturing environment. The sensor can then operate accurately by comparing measurements against these pre-established references.
Solution Approach 2:
The patent utilizes parameter changes by transforming the calibration approach from multi-point temperature measurements to single-point calibration using electrical reference parameters. By using reference voltages or currents with known temperature dependencies (such as bandgap references), the system changes the calibration parameters from requiring multiple temperature measurements to using stable electrical references, thereby reducing calibration time while maintaining accuracy.
2Measurement precision
If calibration is performed throughout the lifetime of the device, then temperature measurement accuracy is improved, but device complexity increases due to requirement of complex circuitry such as analog-to-digital converters
Solution Approach 1:
The patent implements self-service by enabling the temperature sensor to perform its own calibration using internally available reference circuits. The sensor utilizes on-chip reference voltages or currents (such as bandgap references) that are already present in the device, eliminating the need for external calibration equipment or complex analog-to-digital conversion circuitry. This self-calibration capability allows the device to maintain accuracy throughout its lifetime without adding significant complexity.
Solution Approach 2:
The patent applies universality by designing the calibration circuit to use the same reference circuits (such as bandgap references) that are already utilized for other device functions. This multi-functional approach allows the reference circuits to serve both their original purpose and the calibration function, thereby enabling continuous calibration without requiring dedicated calibration-specific hardware, thus avoiding increased device complexity.
3Measurement precision
If multiple devices are calibrated in production, then temperature measurement accuracy is improved, but it becomes difficult to ensure uniform temperature across multiple devices potentially introducing errors
Solution Approach 1:
The patent replaces the mechanical/physical approach of placing multiple devices in a controlled temperature environment for calibration with an electrical substitution method. Each device is calibrated using electrical reference signals (such as voltage or current references with known temperature coefficients) that can be applied individually to each device. This electrical substitution eliminates the need for thermal uniformity across multiple devices during calibration, as each device is calibrated independently using electrical references rather than requiring uniform thermal conditions.
4Reliability
If known temperature protection circuits are used, then device temperature protection is provided, but accuracy is limited and calibration is required
Solution Approach 1:
The patent implements feedback by continuously monitoring the temperature sensor output against reference values and using this information to adjust or validate measurements. The system incorporates feedback mechanisms where the calibrated reference parameters are continuously compared with actual temperature measurements, allowing the device to maintain high accuracy throughout its operation. This feedback approach enables the circuit to compensate for drift and maintain precision without requiring frequent recalibration.
Data Source
AI summary
A circuit for device temperature protection is disclosed. The circuit comprises a Proportional-To-Absolute-Temperature (PTAT) voltage generator. The circuit also comprises at least one comparator. The PTAT voltage generator is configured to apply offset cancellation in a first clock phase. The at least one comparator is configured to evaluate an output of the PTAT generator in a second clock phase. A method of temperature protection of a device is also disclosed.