Resistive Bridge Sensor Temperature Compensation Circuit
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Solution Overview
Problem
Existing MEMS devices with resistive bridge circuits face challenges in temperature compensation, requiring additional electrical connections, increased complexity, higher fabrication costs, and reduced precision due to separate temperature sensing circuits, which complicates accurate measurement of motion status.
Innovation Solution
A circuit that uses a single Wheatstone bridge circuit for both pressure/angle sensing and temperature compensation, employing a driver circuit with operational amplifiers and current mirroring circuits to indirectly measure temperature through bridge resistance, eliminating the need for additional temperature sensing circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate temperature sensing circuit is added to the MEMS device, then temperature compensation capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the temperature sensing function with the existing Wheatstone bridge circuit by using the bridge's inherent temperature-dependent resistance characteristics. The same bridge circuit that senses pressure/angle also provides temperature information through its resistance variations, eliminating the need for a separate temperature sensing circuit and reducing overall device complexity while maintaining temperature compensation capability.
Solution Approach 2:
The Wheatstone bridge circuit is designed to perform multiple functions: primary pressure/angle sensing and secondary temperature sensing. By utilizing the temperature-dependent resistance of the bridge elements, the circuit becomes multi-functional, providing both motion status detection and temperature compensation without requiring additional dedicated components.
2Reliability
If a separate temperature sensing circuit is added to the MEMS device, then temperature compensation capability is improved, but fabrication cost increases
Solution Approach 1:
The patent merges the temperature sensing function into the existing Wheatstone bridge circuit structure. Since the bridge circuit is already part of the MEMS device fabrication process, utilizing its inherent temperature-dependent resistance for temperature sensing eliminates the need for separate temperature sensor fabrication steps, masks, and processing, thereby reducing fabrication costs while achieving temperature compensation.
Solution Approach 2:
The Wheatstone bridge circuit serves itself by using its own temperature-dependent resistance characteristics to provide temperature sensing capability. This self-service approach eliminates the need for external temperature sensing components and their associated fabrication processes, reducing manufacturing complexity and cost.
3Reliability
If a separate temperature sensing circuit is added to the MEMS device, then temperature compensation capability is improved, but measurement precision deteriorates
Solution Approach 1:
The patent combines temperature and motion sensing in a single Wheatstone bridge circuit, but uses different analysis methods to extract information. By measuring the bridge's resistance variations and using the known temperature-dependent sensitivity characteristics, the system can separate temperature effects from motion effects through mathematical processing, maintaining motion status measurement precision while achieving temperature compensation.
Solution Approach 2:
The system uses the temperature information derived from the bridge circuit to apply feedback compensation to the motion status measurement. By continuously monitoring the bridge's temperature-dependent response and adjusting the measurement calculations accordingly, the system compensates for temperature effects and maintains accurate motion status measurement precision.
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 solution enables accurate temperature compensation within the MEMS device, reducing complexity, cost, and precision issues while maintaining precise motion status measurement without additional temperature sensing circuits.
Implementation Method 1
the temperature variation ΔT (i.e., the difference between the actual temperature and some reference temperature) is known
Implementation Method 2
the temperature dependent sensitivity S(T) of the bridge multiplied by the mirror angle σ(t)
Implementation Method 3
employing a driver circuit with operational amplifiers and current mirroring circuits to indirectly measure temperature through bridge resistance
Data Source
Figure 1~3
Figure 4
Figure 5~6
AI summary
A bridge driver circuit (104) applies a bias voltage across first (142) and second (144) input nodes of a resistive bridge circuit (102) configured to measure a physical property such as pressure or movement. A sensing circuit (185) senses a bridge current (Ipbridge, Inbridge) that flows through the resistive bridge circuit (102) in response to the applied bias voltage. A temperature dependent sensitivity of the resistive bridge circuit (102) is determined by processing the sensed bridge current. A voltage output at first (146) and second (148) output nodes of the resistive bridge circuit (102) is processed to determine a value of the physical property. This processing further involves applying a temperature correction in response to the determined temperature dependent sensitivity.