Thermal Sensor Aging Calibration via Dual-Phase Frequency
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Solution Overview
Problem
Aging of resistors and capacitors in thermal sensors within electronic devices, as well as packaging stress, lead to inaccurate temperature sensing, which limits the operating speed of electronic devices like modern mobile devices.
Innovation Solution
A thermal sensor design incorporating a bandgap circuit, dual-phase voltage-to-frequency converter, and frequency meter, which generates temperature-dependent and temperature-independent frequencies to eliminate non-ideal coefficients, ensuring accurate temperature evaluation by combining these frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thermal sensor is placed in a chip for temperature sensing, then temperature monitoring capability is improved, but aging of resistors and capacitors deteriorates sensing accuracy over time
Solution Approach 1:
The patent uses parameter changes by measuring both temperature-dependent parameters (frequency at different temperatures) and temperature-independent parameters (frequency at reference temperature) to characterize aging effects. By tracking how these parameters change over time, the system can compensate for aging-induced accuracy deterioration without requiring physical replacement of components.
Solution Approach 2:
The patent implements feedback by using the measured temperature-independent frequency to calculate an aging compensation factor, which is then applied to correct the temperature-dependent frequency measurements. This closed-loop feedback mechanism continuously compensates for aging effects, maintaining long-term measurement accuracy despite component degradation.
2Ease of manufacture
If packaging stress is applied to the chip, then device integration is improved, but resistor and capacitor values change affecting temperature sensing
Solution Approach 1:
The patent introduces an intermediary measurement approach by using the temperature-independent frequency measurement as a mediator to detect packaging stress effects. This intermediary measurement allows the system to separate stress-induced parameter changes from temperature-induced changes, enabling accurate temperature sensing despite packaging stress on the components.
Solution Approach 2:
The patent applies segmentation by separating the frequency measurement into two distinct phases: temperature-dependent measurements for actual temperature sensing and temperature-independent measurements for stress/aging compensation. This segmentation allows independent characterization and compensation of different error sources affecting the sensor.
3Measurement precision
If calibration is performed to compensate for aging, then long-term accuracy is improved, but additional measurement time and complexity are required
Solution Approach 1:
The patent merges the calibration function into the normal temperature sensing operation by using the same voltage-to-frequency converter circuit for both temperature measurements and aging compensation measurements. This merging eliminates the need for separate calibration hardware and reduces overall system complexity while maintaining long-term accuracy.
Solution Approach 2:
The patent implements self-service calibration where the sensor automatically performs its own aging compensation by measuring both temperature-dependent and temperature-independent frequencies and calculating the compensation factor internally. This self-calibrating approach eliminates the need for external calibration equipment or complex manual calibration procedures.
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
This approach provides reliable and accurate temperature data, enabling effective optimization of electronic device operations by eliminating the impact of aging and packaging stress on sensor accuracy.
Implementation Method 1
The bandgap circuit outputs a temperature-dependent voltage
Data Source
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AI summary
A thermal sensor with non-ideal coefficient elimination is shown. The thermal sensor has a bandgap circuit, a dual-phase voltage-to-frequency converter, and a frequency meter. The bandgap circuit outputs a temperature-dependent voltage. The dual-phase voltage-to-frequency converter is coupled to the bandgap circuit in the normal phase to perform a voltage-to-frequency conversion based on the temperature-dependent voltage, and is disconnected from the bandgap circuit in the coefficient capturing phase to perform the voltage-to-frequency conversion based on the supply voltage. The frequency meter is coupled to the dual-phase voltage-to-frequency converter to calculate the temperature-dependent frequency corresponding to the normal phase of the dual-phase voltage-to-frequency converter. The frequency meter also calculates the temperature-independent frequency corresponding to the coefficient capturing phase of the dual-phase voltage-to-frequency converter. The temperature-dependent frequency and the temperature-independent frequency are provided for temperature evaluation with non-ideal coefficient elimination.