Patent ID: 7289924

Claim:
A self-calibrating sensor comprising a piezo-resistive pressure sensor, and a calibration circuit comprising a bias controller, coupled to an input of said a piezo-resistive pressure sensor, for adjusting a bias parameter of the a piezo-resistive pressure sensor, differential circuitry having a first input for receiving an output signal of said piezo-resistive pressure sensor, a second input for receiving a predetermined reference signal, and an output, coupled to an input of said bias controller, for providing a control signal according to the deviation between said predetermined reference signal and said output signal, and a calibration switch operatively connected to said differential circuitry and/or said bias controller for switching the operating mode of the system between a calibration mode and a normal mode, whereby, in calibration mode, said biasing controller, in response to receiving said control signal, can increment or decrement the operating bias point of the piezo-resistive pressure sensor by adjusting the bias voltage/current to bridge resistors connected thereto to substantially eliminate said deviation thereby providing a sensor output signal corresponding to said predetermined reference signal, and whereby, in normal mode, said piezo-resistive pressure sensor can operate at the calibrated operating bias point.