MOS integrated high sensitivity MEMS Piezoresistive pressure sensor without Wheatstone Bridge

Abstract: Wheatstone bridge circuit is generally employed in Piezoresistive pressure sensor having four piezoresistors used to convert the magnitude of the applied pressure into a proportional change in resistance. Linear relationship between the applied pressure and the change in resistance is possible in piezoresistive pressure sensors. The differential voltage obtained from the Wheatstone bridge circuit is further amplified using signal conditioning circuit to realize large voltage sensitivity. The recent trend in industrial applications prefers a current output from the pressure sensors for transmission to the control room from the remote sensing location. The current practice is to convert the voltage obtained from differential amplifier into a proportional current in the piezoresistive pressure sensors. In this work, the authors introduce a simple technique that directly converts change in piezoresistance into a current using MOSFET current amplifiers. MOS integrated pressure sensor is introduced, since it is possible to integrate MOSFETs in silicon using Micro Electro Mechanical Systems so that the piezsoresistive mechanism and current transmitter can be integrated in a single chip.

Keywords: Micro electro mechanical systems; Metal oxide semiconductor field effect transistor; Piezoresistor; Sensitivity; IntelliSuite; pSPICE.