Silicon Piezoresistive Bridge Thermal Offset Physics Basics
Silicon piezoresistive thermal offset stems from resistor TCR imbalances and package thermal stress, requiring targeted drive excitation and polynomial compensation.
Polynomial Thermal Compensation
Mathematical Correction
Algorithmic adjustment of sensor outputs using multi-order equations corrects the non-linear errors introduced by ambient temperature changes. Advanced sensing systems implement polynomial thermal compensation to calculate a corrected value using the measured temperature as an independent variable. This technique utilizes coefficients generated during a multi-point calibration process to neutralize the non-linear behavior of the transducer element.
It represents the primary method for achieving high accuracy in digital pressure and load sensors.
Algorithmic Correction
Applying this mathematical correction requires the embedded microprocessor to execute a polynomial calculation on each incoming measurement. The algorithm reads the raw digit from the pressure sensing element and the digit from an adjacent temperature sensor, then computes the correction factor. This real-time computation applies the unique calibration coefficients stored in the non-volatile memory of the device.
This process occurs within the analog-to-digital conversion cycle to avoid adding latency to the output signal.
Thermal Characterization
Generating the coefficients requires exposing the sensor to several stable temperature points across its rated operating range. A least-squares regression algorithm then calculates the polynomial curve that best matches the recorded thermal drift pattern.
Operating Range
Environmental limits define the boundary where the polynomial compensation remains effective. Beyond these limits, the mathematical model can diverge rapidly from the actual physical behavior of the sensor, causing significant errors. This limitation necessitates strict boundaries on the operational temperature range specified for the calibrated transmitter.