A passive UHF RFID pressure sensor tag with a 7.27 bit and 5.47pJ capacitive sensor interface

A full passive UHF pressure RFID tag is presented in this work. Special attention is paid to the novel capacitive sensor-interface and the analog FE which were designed and implemented on a low cost 0.35µm standard CMOS technology. The characterization of the fabricated sensor interface connected to a pressure MEMS transducer shows a fully digital output with an ENOB of 7.27 bits and an FOM of 5.47pJ. The fabricated analog front-end, assembled to a matched dipole antenna, was connected to the digital core and the implemented pressure sensor. The RFID pressure sensor tag was characterized inside a PVC pressure chamber. Successful ID and pressure measurement (30kPa–120kPa) communication with a commercial RFID reader over a distance of 1.5m was achieved using the EPC Gen 2 standard. These characteristics allow the use of the proposed system in long range wireless pressure sensing and motivates the implementation of the proposed capacitive sensor interface in passive wireless sensors.