Digital output MEMS pressure sensor using capacitance-to-time converter

Abstract

In this paper, a MEMS capacitive pressure sensor and a capacitance to digital converter are presented. The MEMS transducer has been designed and fabricated using MetalMUMPs process from MEMSCAP. For an diaphragm area of 600×600 μm2 and an electrostatic pressure variation up to 30 kPa, the MEMS exhibits a capacitance change from 9.3 pF to 13.4 pF, with a INL of 0.2% A capacitance to digital converter has been designed and fabricated in a low cost 2P4M 0.35μm CMOS standard process as a digital interface to the MEMS sensor. The measured resolution of 7.9 bit and power consumption of 16.56 μW demonstrate that by combining both devices a long range passive RFID sensor for pressure measurements up to 30 kPa is achieved.