Bridge Circuit Bias Voltage Correction for Sensor Accuracy
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Solution Overview
Problem
Existing sensor devices with bridge circuits face accuracy issues due to the need for variable gain amplification circuits, which introduce discontinuous noise or distortion when correcting output voltage values, leading to deterioration of detection output accuracy.
Innovation Solution
The sensor device incorporates a bridge circuit that functions as a multiplication circuit, allowing it to compensate for changes in its characteristics by adjusting the bias voltage based on calculated impedance, eliminating the need for variable gain amplification circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a variable gain amplification circuit is used to correct output voltage values, then the correction of output voltage can be achieved, but discontinuous noise is superimposed on the output voltage or the output voltage is distorted, leading to deterioration of detection output accuracy
Solution Approach 1:
The patent extracts the correction function from a separate variable gain amplification circuit and integrates it directly into the bridge circuit by making the bridge circuit itself perform the multiplication operation. This eliminates the need for external correction circuits that generate noise and distortion.
Solution Approach 2:
The patent merges the correction function with the bridge circuit by having the bridge circuit perform both its sensing function and the multiplication/correction operation simultaneously. This integration eliminates the interface between separate correction circuits and the bridge circuit, preventing noise and distortion.
2Measurement precision
If the gain of an amplification circuit is changed for correction, then the output voltage value can be corrected, but the device complexity increases due to the need for variable gain amplification circuits
Solution Approach 1:
The patent removes the separate variable gain amplification circuit from the system and extracts its correction function, implementing it instead within the bridge circuit through direct multiplication operation, thereby simplifying the overall device structure.
Solution Approach 2:
The bridge circuit is designed to perform multiple functions: it serves as both the sensing element and the multiplication/correction circuit. This multi-functionality eliminates the need for separate correction circuits, reducing device complexity.
3Adaptability or versatility
If a variable gain amplification circuit with linear analog voltage signal is used, then the gain can be set continuously, but the output voltage of the amplification circuit is likely to be distorted
Solution Approach 1:
The patent extracts the gain adjustment function from a separate amplification circuit and implements it within the bridge circuit itself, eliminating the distortion issues associated with external variable gain amplification circuits while maintaining continuous adjustment capability.
Solution Approach 2:
Instead of using a separate amplification circuit to perform the multiplication operation, the patent implements the multiplication function directly within the bridge circuit, creating a faithful copy of the correction operation without the intermediate amplification stage that causes distortion.
Data Source
AI summary
In a sensor device, a bias circuit includes a bias voltage generation circuit, a regulator circuit, an impedance calculation circuit, and a bias voltage correction circuit. The bias voltage generation circuit generates a bias voltage required to operate the bridge circuit. The regulator circuit applies the bias voltage to the bridge circuit and monitors a bias current supplied to the bridge circuit. The impedance calculation circuit receives a value of the bias voltage and a value of the bias current and calculates an impedance of the bridge circuit. Based on the impedance, the bias voltage correction circuit causes the bias voltage to be corrected to a voltage that compensates for a change in characteristics of the bridge circuit.