A 350 mu W CMOS MSK Transmitter and 400 mu W OOK Super-Regenerative Receiver for Medical Implant Communications

Abstract

Recent advances in the medical field are spurring the need for ultra-low power transceivers for wireless communication with medical implants. To deal with the growing demand for medical telemetry, the FCC commissioned the medical implant communications services (MICS) standard in 1999 in the 402-405 MHz band. This paper presents a 350 muW FSK/MSK direct modulation transmitter and a 400 muW OOK super-regenerative receiver (SRR) specifically optimized for medical implant communications. The transceiver is implemented in 90 nm CMOS and digitally tunes 24 MHz in frequency steps smaller than 2 kHz. The transmitter meets MICS mask specifications with data rates up to 120 kb/s consuming only 2.9 nJ/bit; the receiver has a sensitivity better than -99 dBm with a data rate of 40 kb/s or -93 dBm with a data rate of 120 kb/s consuming 3.3 nJ/bit. A frequency correction loop incorporating the base-station is prototyped to eliminate the need for a frequency synthesizer in the implant while still achieving frequency stability of less than 3 ppm.