An 11 uW Sub-pJ/bit Reconfigurable Transceiver for mm-Sized Wireless Implants

A wirelessly powered 11 $\mu {\rm W}$ transceiver for implantable devices has been designed and demonstrated through 35 mm of porcine heart tissue. The prototype was implemented in 65 nm CMOS occupying 1 mm $\,\times\,$ 1 mm with a 2 mm $\,\times\,$ 2 mm off-chip antenna. The IC consists of a rectifier, regulator, demodulator, modulator, controller, and sensor interface. The forward link transfers power and data on a 1.32 GHz carrier using low-depth ASK modulation that minimizes impact on power delivery and achieves from 4 to 20 Mbps with 0.3 pJ/bit at 4 Mbps. The backscattering link modulates the antenna impedance with a configurable load for operation in diverse biological environments and achieves up to 2 Mbps at 0.7 pJ/bit. The device supports TDMA, allowing for operation of multiple devices from a single external transceiver.