Characterization of a Tilted-beam Piezoresistive MEMS Sensor with Current-drive Readout Circuit

The sensing properties of a microelectromechanical system (MEMS)-based displacement sensor with a constant-current (CC) readout circuit are explored. The sensor comprises a pair of tilted clamped-guided silicon beams whose bulk piezoresistivity are employed for displacement sensing. To investigate the effect of driving the sensor with constant current, a readout circuit is designed and implemented. The characteristics of the sensor with the CC circuit are compared with the results obtained from a previously implemented Wheatstone half-bridge. To ensure a fair comparison, two test scenarios are considered. In the first approach, parameters of CC circuit are tuned such that the same power is delivered to the sensing beams. In the second case, these parameters are chosen so that both circuits achieve equal gains. A thorough characterization of the sensor is preformed in terms of linearity, resolution, bandwidth and noise. The results reveal that the piezoresistive sensor with the CC readout circuit provides a superior linearity compared to the Wheatstone bridge. However, using this circuit comes with challenges including a poor noise performance which are also discussed here.