PGA Offset Compensation Circuit for Pressure Sensor Bridge Drift
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Solution Overview
Problem
Pressure sensors with resistive bridges face significant zero-pressure offset voltages due to imperfections in construction, such as resistor mismatch, which dominate the output signal and hinder accurate pressure measurement, requiring complex signal conditioning calculations.
Innovation Solution
A programmable gain amplifier (PGA) based offset voltage compensation circuit that applies an offset compensation voltage to either the input or output loop to cancel the zero-offset voltage, proportional to the bias voltage, allowing for accurate pressure sensing without requiring calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex signal conditioning calculations are used to compensate for offset voltage, then measurement precision may be improved, but device complexity increases
Solution Approach 1:
The patent extracts the offset voltage compensation function from complex signal conditioning calculations and implements it through a dedicated compensation circuit that applies an offset compensation voltage directly to the amplifier input or output, thereby eliminating the need for complex computational compensation while maintaining measurement precision
Solution Approach 2:
The patent introduces an offset compensation voltage as an intermediary element that mediates between the sensor output and the amplifier, allowing direct electrical compensation of the offset voltage without requiring complex signal processing calculations
2Measurement precision
If offset compensation voltage is applied, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent implements offset compensation by changing the voltage parameter (applying an offset compensation voltage) to directly counteract the zero-pressure offset voltage, providing a simple and effective solution that improves sensor accuracy without introducing complex circuitry
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
Effectively cancels zero-pressure offset voltages, enabling precise pressure measurement by isolating the physical quantity signal from the offset voltage, independent of the bias voltage and gain settings, thus improving sensor accuracy.
Implementation Method 1
the strain gauges utilize the piezoresistive effect such that the resistance of the strain gauges increases as pressure deforms the material of the strain gauges
Data Source
AI summary
A sensor offset voltage compensation circuit includes a programmable gain amplifier (PGA) having an input loop configured to receive the signal output by a sensor (e.g., a voltage generated a sensor resistive bridge of a pressure sensor) and an output loop configured to furnish an output signal having a voltage that is greater than the input voltage. An offset compensation voltage is applied to at least one of the input loop or the output loop of the PGA to at least substantially cancel the zero-quantity offset voltage of the sensor from the output voltage.