A 2m-Range 711μW Body Channel Communication Transceiver Featuring Dynamically-Sampling Bias-Free Interface Front End

Abstract

Body Channel Communication (BCC) utilizes the body surface as a low-loss signal transmission medium, reducing the power consumption of wireless wearable devices. However, the effective communication range on the human body is limited in the state-of-the-art BCC transceivers, where the signal loss between the body surface and the BCC receiver remains one of the main bottlenecks. To reduce the interface loss, a high input impedance is desired by the BCC receiver, but the DC-biasing circuits decrease the input impedance. In this work, a dynamically-sampling IFE is proposed to eliminate the DC voltage bias, resulting in a 90k$\Omega$ high input impedance and a 94dB RF$-$IF conversion gain to reduce the interface loss in long-range BCC applications. The BCC transceiver chip is fabricated in 55nm CMOS process, taking a die area of 0.123mm${}^{2}$. Measured results show that the chip extends the BCC range to 2m for both the forward and backward paths, where the transmitter and receiver consume 711$\mu$W power in total.