A 1.1mW Hybrid OFDM Ground Effect-Resilient Body Coupled Communication Transceiver for Head and Body Area Network

Abstract

A Hybrid OFDM transceiver for the head-and body-area network is presented. This is the first transceiver in the literature that mitigates all the body channel impairments at once. It combines baseband BPSK-OFDM with FSK to alleviate the impacts of variable ground effect and signal multipath on the body channel quality with measured BER improvement of >70% compared to FSK modulation. It can tolerate up to 20dB of channel gain variation. Skin-electrode contact impedance variation is also continuously monitored and compensated at both TX and RX. An 8-point FFT/IFFT with no floating point multipliers is utilized in H-OFDM TX and RX that reduces the gate count by 54% compared to conventional floating point multipliers. A glitch-free FSK demodulation RX with variable threshold limiter and all digital cycle correction is proposed to support a scalable data rate (200Kbps-2Mbps). The 0.54mm(2) transceiver in 65nm CMOS consumes 1.1mW.