Thermal Sensor Differential Circuit for Supply-Voltage Compensation
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Solution Overview
Problem
Thermal sensors are affected by variations in supply voltage, leading to reduced accuracy due to noise and inaccuracy in measurements, and highly stable voltage sources are costly.
Innovation Solution
A thermal sensor design that includes a differential circuit with a sensing element and a reference element, along with a controller to measure the supply voltage and perform differential measurements to correct for voltage variations, using a bridge circuit to cancel out common-mode effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If highly stable supply voltage sources and circuitry are used to mitigate voltage variations, then measurement accuracy is improved, but device cost increases significantly
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously measures the actual supply voltage and uses this information to compensate for voltage variations in the sensor output. The controller obtains a measured supply voltage value, performs differential measurements between sensing and reference elements, and determines a corrected sensor output value based on both the differential measurement and the measured supply voltage, thereby eliminating the need for expensive stable voltage sources
Solution Approach 2:
The patent introduces a reference element as an intermediary that experiences the same supply voltage variations as the sensing element but is not affected by the target stimulus. By comparing the sensing element output with the reference element output through differential measurement, the common-mode voltage variations are rejected, allowing accurate measurements without requiring expensive stable voltage sources
2Reliability
If supply voltage is stabilized using expensive components, then noise and inaccuracy are reduced, but overall sensor cost increases
Solution Approach 1:
The controller measures the actual supply voltage and uses this feedback to compensate for voltage variations in real-time. By obtaining the measured supply voltage value and using it to correct the sensor output, the system maintains high reliability and accuracy without requiring expensive stable voltage sources or circuitry
Solution Approach 2:
The sensor system performs its own voltage compensation by measuring the supply voltage internally and using this information to correct its output. The controller self-corrects for voltage variations by combining the differential measurement with the measured supply voltage value, eliminating the need for external expensive stabilization components
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
Improves measurement accuracy by compensating for resistance variations caused by voltage fluctuations without the need for expensive components, enhancing sensitivity and reducing noise.
Implementation Method 1
Thermal sensors use a sensing element to detect a change when the heating element is exposed to a target stimulus
Implementation Method 2
the sensing element may detect a change in resistance of a heating element or a change in the current or voltage applied to it
Data Source
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AI summary
A thermal sensor comprising: a supply voltage input configured to receive a supply voltage; a differential circuit, the differential circuit comprising a first element configured to provide a first sensing signal, and a first reference element configured to provide a first reference signal; and a controller configured to: obtain a measured supply voltage value, the measured supply voltage value corresponding to a measurement of the supply voltage received by the supply voltage input; obtain a differential measurement between the first sensing signal and the first reference signal; and determine a sensor output value based on the measured supply voltage value and the differential measurement. A method for operating a thermal sensor is also described.