Biomedical implant transceiver with novel multi level LSK back telemetry and fully digital BPSK demodulation

Abstract

Low power consumption and higher data rate is desired in biomedical implant transceivers. A novel fully digital Binary Phase Shift Keying (BPSK) demodulator and a multi-level Load Shift Keying (LSK) for passive back telemetry are implemented to reduce the power consumption and increase the data rate for implant transceivers. The digital architecture allows the BPSK demodulator to consume much less power compared to prior art. We demonstrate silicon realization of the BPSK demodulator operating at 13.56MHz with data rate as high as 800kbits/s in a 0.5µm CMOS process with power consumption of 2.3mW. A multi-level Load Shift Keying (LSK) for passive back telemetry is implemented using discrete components and works by modulating the load impedance at the implant to create distinct reflections at the primary coil of the reader. The back telemetry techniques is verified through simulation and measurement results and demonstrate a 2X improvement in data rate compared to conventional bi-level back telemetry.