Semiconductor pressure sensor utilizing capacitance change

Abstract

An S/N ratio of an output of a semiconductor pressure sensor is improved, the sensor being of an electrostatic capacitance type pressure sensor for generating an output based upon a ratio between capacitances of a pressure sensitive capacitance element and a reference capacitance element. This semiconductor pressure sensor has: a pressure sensitive capacitance element having an electrostatic capacitance Cs changing with a pressure to be detected; a reference capacitance element having an electrostatic capacitance Cr not changing with the pressure; and a unit for detecting the pressure by outputting a signal corresponding to a ratio between the capacitances Cs and Cr, wherein an initial value Cr0 of the capacitance Cr and an initial value Cs0 of the capacitance Cs are defined by 1.2<Cr0/Cs0<1.8. The Cr0/Cs0 ratio is adjusted by changing the electrode area or the like of both the elements. In this manner, it is possible to obtain a large pressure gauge output ΔV, lower an amplification factor of the amplifier, and provide a high precision of the sensor.

Dependencies are inferred from the claim text.