Digital compensated capacitive pressure sensor using CMOS technology for low-pressure measurements☆

Abstract A capacitive pressure sensor with digital output for low-pressure measurements has been fabricated using CMOS technology. The sensor output is compensated and adjusted by a newly developed method. The sensor has a hybrid configuration of an integrated sensor chip and a digital IC chip. Because of this configuration, the thermal sensitivity shift and thermal zero shift of the output are adjusted at the sensor chip, while the offset and full-scale span of the output are adjusted at the digital IC chip, independently. By using the new compensation and adjustment technique, a thermal sensitivity shift of 0.026% FS/°C and thermal zero shift of 0.013% FS/°C for a pressure range of 0-200 mm H 2 O (0-20.39 Pa) and a temperature range of 25–75 °C have been obtained. These characteristics using the new compensation method are about 1/7 and 1/4 of those obtained by using a conventional method. Furthermore, a humidity countermeasure is proposed.