Research of MEMS Pressure Sensor Stability With PDA-NFL Circuit

The stability of pressure sensor chip output characteristics using the piezoresistive method in the form of microelectromechanical system (MEMS) is one of the most important features for sensors. The research analyzes the changes in the useful signal, as well as errors of highly sensitive pressure sensor chips. The main feature of this development is the application of a new electrical circuit in the form of piezoresistive differential amplifier with negative feedback loop (PDA-NFL) utilizing bipolar junction transistors (BJTs), which allows to achieve a balance between high sensitivity, small chip area, and low errors. This research considers the variations of two batch with pressure sensor chip PDA-NFL samples (area $4.00\times 4.00$ mm2) for the range of 1 kPa after 4.5 years [eight samples, sensitivity ${S}_{\text {1 after}} =$ ( $40.6~\pm ~6.4$ ) mV/V/kPa, nonlinearity $2K_{\text {NL 1 after}} =$ ( $0.81~\pm ~0.15$ )%/FS] and range of 5 kPa after 3.0 years [14 samples, sensitivity ${S}_{\text {5 after}} =$ ( $11.2~\pm ~1.8$ ) mV/V/kPa, nonlinearity $2K_{\text {NL 5 after}} =$ ( $0.10~\pm ~0.06$ )%/FS]. The study demonstrates the unidirectional influence of residual mechanical stresses (RMS) from the pressure sensor assembly design on sensitivity and nonlinearity when pressure is applied from different sides of chip and temperature hysteresis errors.