A very low power 7.9 bit MEMS pressure sensor suitable for batteryless RFID applications

There is a strong motivation for the development of new low power sensors for wireless passive applications such as RFID. In this work, a combination of a MEMS capacitive pressure transducer and a capacitive to digital converter compatible with a sensor enabled RFID tag are presented. The MEMS transducer has been designed and fabricated using a MetalMUMPs process. Its characterization showed an output variation between 9.3 pF and 13.4 pF corresponding to a pressure variation between 0 kPa and 30 kPa, with a INL of 0,2%. On the other hand, the capacitance to digital converter has been implemented in a low cost 2P4M 0.35μm CMOS standard process. The interface measurements showed a resolution of 7.8 bit and an average power consumption of 16.56 μW. Combining both devices together with a sensor enabled RFID tag, a long range passive RFID sensor for pressure measurements up to 30 kPa could be implemented.