Drift Characterization
Systematic variation in zero-input output voltage or digital code produced by an inertial sensor across its operating temperature range defines baseline bias instability. Evaluating zero rate offset thermal drift measures how much a micro-electromechanical gyroscope output deviates from zero angular velocity as ambient temperature changes. The parameter applies to stationary inertial sensors in the absence of applied rotation, stopping where dynamic g-sensitivity and vibration-induced offsets dominate.
Data sheets express this drift in degrees per hour per degree Celsius.
Mechanical Deformation
Thermal expansion mismatch between silicon MEMS structures, glass substrates, and organic package materials generates asymmetric internal mechanical stress. As temperature changes, thermal stress deforms comb-finger sensing elements and shifts capacitance balance in micro-machined proof masses. Quadrature error signals increase, causing the demodulated DC offset output to wander.
High precision sensor packaging utilizes stress-isolating die attach adhesives to mitigate thermal strain transfer.
Compensation Matrix
Factory calibration procedures sweep assembled inertial measurement units through controlled thermal profiles inside environmental chambers while keeping rotation rates at zero. Integrated temperature sensors record die temperature alongside raw offset outputs across the full thermal range. Calibration software fits high-order polynomials or multi-segment lookup tables to the collected temperature-drift curves.
Onboard microcontrollers apply these compensation coefficients in real time to cancel bias drift before outputting rate data.
Environmental Testing
Automated test stations verify residual drift after polynomial compensation by cycling finished sensors through thermal ramp cycles. Units showing uncompensated bias drift exceeding published limits are rejected during final calibration. Verification confirms stability across storage and operating thermal extremes.
