Abstract
This paper describes an inductively powered 27-Mbps, 0.08-mm(3) CMOS transceiver with integrated RF receiver coils for simultaneous two-way, near-field data telemetry and power transmission for implantable systems. A four-coil inductive link operates at a 27-MHz carrier for power and a 700-MHz carrier for data telemetry with the antennae taking an area of only 2 mm by 2 mm. Amplitude-shift-keying (ASK) modulation is used for data downlink at 6.6 kbps and load-shift keying (LSK) backscattering is used for data uplink at 27 Mbps. The transceiver consumes 2.7 mW and can power a load consuming up to an additional 1.5 mW. Implemented in a 0.18-um silicon-on-insulator (SOI) technology, post-processing steps are used to decrease chip thickness to approximately 15um, making the chip flexible with a tissue-like form factor and removing the effects of the substrate on coil performance. Power harvesting circuitry, including passive rectifier, voltage regulator, RF limiter, ASK and LSK modulator, clock generator, and digital controller are positioned adjacent to the coils and limited to an area of 0.5 mm by 2mm. Complete transceiver functionality of the system has been achieved with overall power transfer efficiency (PTE) of 1.04% through 1 mm of tissue phantom between reader and implant.