SEMICONDUCTOR PRESSURE SENSOR

摘要

PURPOSE: To improve the S/N ratio of sensor output, in electrostatic type capacity pressure sensor generating an output depending on the ratio of a pressure sensitive capacitance to a reference capacitance. CONSTITUTION: The semiconductor pressure sensor is provided with a pressure sensitive capacitance element 2 having a pressure sensitive capacitance Cs with an electrostatic capacity variable depending on a pressure to be detected, a reference capacitance element 3 having a reference capacitance Cr with an electrostatic capacity invariable by a pressure to be detected, and a means for detecting a pressure by outputting a signal corresponding to the ratio of the pressure sensitive capacitance Cs to the reference capacitance Cr. The relationship between an initial value Cr0 of the reference capacitance Cr and an initial value Cs0 of the pressure sensitive capacitance Cs is 1.2 < Cr0/Cs0 < 1.8. The ratio of Cr0/Cs0 is adjusted by differentiating areas of electrodes of respective elements and the like. Thus, a pressure gauge outputΔV is increased and an amplification ratio of an amplifier is decreased to improve the ratio S/N, thereby realizing the sensor with high precision.