A 23 µA RF-powered transmitter for biomedical applications

We propose a new tag architecture that employs an active transmitter to decouple the frequencies used for power and data telemetry. Receiving power at 918 MHz and transmitting data at 306 MHz eliminates the “self-jamming” problem presented to RFID readers, reducing the complexity of reader design. This scheme allows remote placement of the data receiver and extends the data transmission range. Our transmitter uses subharmonic injection-locking to avoid power hungry LO generation circuitry while eliminating the need for quartz crystals. The tag prototype was fabricated using a 0.13 µm CMOS process, occupying 0.3 mm2 active area. With an on-off keying (OOK) data rate of 4 Mbps, the 23 µA transmitter with an output power of −33 dBm achieves an energy efficiency of 10 pJ/bit, the best reported to date for such systems.