A bipolar integrated silicon pressure sensor

A bipolar integrated piezoresistive-type silicon pressure sensor with frequency-modulated output where frequency is related to the applied pressure has been developed. The sensor peripheral circuits were fabricated in a standard bipolar process and the shaping of the sensor was accomplished using an EDP anisotropic etchant. Signal conditioning circuitry consists of a band-gap voltage reference circuit, a differential amplifier, and a current-controlled oscillator. This circuit is designed to stabilize change in sensitivity due to variations in temperature and supply voltage.<>