A Low-Power and Small Chip-area Multi-rate Human Body Communication DPFSK Transceiver for Wearable Devices

A low-power and small chip-area multi-rate human body communication (HBC) discontinuous-phase FSK (DPFSK) transceiver applied for wearable devices is presented. The transceiver is implemented in UMC $0.18~\mu \text{m}$ CMOS process with a small chip area of only 0.46 mm ² . DPFSK modulation is adopted to reduce the hardware complexity of the transceiver. In the receiver, a direct-conversion front-end is adopted to eliminate polarization voltage of the electrode-skin interface. A delay line (DL)-based variable phase shifter used in the demodulator of the receiver is proposed for accomplishing of multi-rate DPFSK demodulation. In the transmitter, a digital frequency interpolator is adopted for achieving multi-rate DPFSK transmission. At a data rate of 1 Mb/s, the receiver and the transmitter consume the power of 1.79 mW and $700~{\boldsymbol{\mu }}\text{W}$ , respectively. Therefore, energy consumption per received and transmitted bit are 1.79 nJ/bit and 0.7 nJ/bit, respectively.