A Signal Conditioning Circuit for Piezoresistive Pressure Sensors With Variable Pulse-Rate Output

A signal conditioning circuit with variable pulse-rate 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 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 a very advantageous SPICE model for piezoresistive sensors is introduced. Simulation as well as experimental results are included to demonstrate the performance of the circuit.

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