A Re-Configurable Body Channel Transceiver Towards Wearable and Flexible Biomedical Sensor Networks

Body channel communication (BCC) has become a promising candidate in wireless body area networks (WBAN) due to its advantages in energy efficiency and security. However, BCC transceivers face two challenges: diverse application requirements and varying channel conditions. To overcome these challenges, this article proposes a re-configurable architecture for BCC transceivers (TRXs), whose key parameters and communication protocols can be software-defined (SD) according to the requirements. In the proposed TRX, the programmable direct-sampling receiver (RX) is a combination of a programmable low-noise amplifier (LNA) and a fast-convergent successive approaching register analog-to-digital converter (SAR ADC), to achieve simple but energy-efficient data reception. The programmable digital transmitter (TX) is essentially implemented by a 2-bit DAC array to transmit either wide-band carrier-free signals like 4-level pulse amplitude modulation (PAM-4) or non-return-to-zero (NRZ) or narrow-band carrier-based signals like on-off keying (OOK) or frequency shift keying (FSK). The proposed BCC TRX is fabricated in a 180-nm CMOS process. Through an in-vivo experiment, it achieves up to 10-Mbps data rate and 119.2 pJ/bit energy efficiency. Moreover, the TRX is able to communicate under long-distance (1.5 m) and body-shielding conditions by switching its protocols, which shows the potential to be deployed in all categories of WBAN applications.