Calibration Circuit for Pressure Sensor Gain Correction
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Solution Overview
Problem
Conventional pressure sensing devices with capacitive sensors face inaccuracies due to poor manufacturing and noise affecting the conversion of sensing capacitance to pressure values, leading to incorrect estimations.
Innovation Solution
A calibration circuit is introduced, comprising a gain generating circuit and a processor, which utilizes a passive component to obtain a calibration gain factor for the converter, allowing for accurate calibration of digital signals and conversion of sensing signals to pressure values, especially in regular operating and built-in self-detection modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional converters are used without calibration, then the device complexity is reduced, but the measurement precision deteriorates due to manufacturing variations and noise affecting capacitance-to-pressure conversion accuracy
Solution Approach 1:
The patent applies preliminary action by performing calibration before regular operation. A calibration circuit with known capacitance values is connected to the converter during a calibration phase to establish accurate conversion parameters. These parameters are then stored and used during regular pressure sensing operations, ensuring measurement precision without adding complexity to the operational circuit.
Solution Approach 2:
The patent uses an intermediary calibration circuit that mediates between the converter and the final pressure measurement. This calibration circuit includes known capacitance elements and control switches that allow the system to determine accurate conversion factors without requiring the converter itself to be perfectly precise. The intermediary calibration setup enables precise measurements while keeping the main sensing circuit simple.
2Manufacturing precision
If a calibration circuit with passive components is added, then the manufacturing precision is improved through gain factor calibration, but the device complexity increases due to additional circuit components
Solution Approach 1:
The calibration circuit performs manufacturing precision correction during an initial calibration phase. Passive components with precise known values are connected to the converter to measure and store accurate conversion gain factors. Once calibrated, these factors are saved and used during normal operation, achieving high manufacturing precision without requiring the calibration components to remain connected, thus minimizing ongoing complexity.
Solution Approach 2:
The patent extracts the calibration function from the regular operational circuit. The calibration circuit is activated only during calibration mode using control switches, and then disconnected or deactivated during normal pressure sensing. This separation allows the system to achieve high manufacturing precision through calibration while maintaining simple operational circuitry, as the calibration components are 'taken out' from the active operational path.
3Reliability
If calibration is performed using built-in self-detection mode with predetermined capacitor, then the reliability is improved through error correction, but the ease of operation deteriorates due to mode switching requirements
Solution Approach 1:
The system performs calibration as a preliminary action during device initialization or setup phase. The built-in self-detection mode with predetermined capacitor automatically executes calibration routines before the device enters regular pressure sensing mode. This preliminary calibration ensures high reliability of subsequent measurements without requiring user intervention during normal operation, as the calibration is completed upfront.
Solution Approach 2:
The calibration circuit implements self-service through automatic built-in self-detection mode. The system automatically switches to calibration mode, connects the predetermined capacitor, performs gain factor measurement and storage, then returns to normal operation without user intervention. This self-service calibration process improves reliability while minimizing the impact on ease of operation, as the mode switching is automated and transparent to the user.
Data Source
AI summary
The present disclosure illustrates a calibration circuit for a pressure sensing device. The calibration circuit, via at least one passive component installed in the pressure sensing device, obtains a calibration gain factor of at least one converter also installed in the pressure sensing device, and when the pressure sensing device is in a regular operating mode, the calibration gain factor can be used to calibrate the output of the converter, so that a sensing signal inputted into the pressure sensing device can be correctly converted to a relevant pressure value.