An Integrated Full-Wave CMOS Rectifier With Built-In Back Telemetry for RFID and Implantable Biomedical Applications

This paper describes the design and implementation of an integrated full-wave standard CMOS rectifier with built-in passive back telemetry mechanism for radio frequency identification (RFID) and implantable biomedical device applications. The new rectifier eliminates the need for additional large switches for load modulation and provides more flexibility in choosing the most appropriate load shift keying (LSK) mechanism through shorting and/or opening the transponder coil for any certain application. The results are a more robust back telemetry link, improved read range, higher back telemetry data rate, reduced rectifier dropout voltage, and saving in chip area compared to the traditional topologies. A prototype version of the new rectifier is implemented in the AMI 0.5- mum n-well 3-metal 2-poly 5 V standard CMOS process, occupying ~ 0.25 mm2of chip area. The prototype rectifier was powered through a wireless inductive link and proved to be fully functional in its three modes of operation: rectification, open coil (OC), and short coil (SC).