A piezoresistive pressure sensor interfacing circuit

A signal conditioning circuit with digital output for piezoresistive pressure sensors based on CMOS current mode building blocks is presented. The proposed circuit uses an instrumentation amplifier (IA) based on operational floating amplifiers (OFA), adapted for resistive sensors. This IA offers a output current which is independent of tracking and offset errors. Two piezoresistors with current supply are used against four piezoresistors of the basic Wheatstone bridge. A new temperature compensation technique for the pressure sensitivity is described. Also an accurate SPICE model for piezoresistive sensors is introduced. Simulation as well as experimental results are included to demonstrate the performance of the circuit.