Abstract
Conventional wireless approaches for wearable body sensor networks suffer from body shadowing effects and high power consumption. Human body communication (HBC) utilizing the body's conductive properties offers a promising alternative but faces challenges from dynamic channel characteristics and environmental interference coupling in the sub-10 MHz electro-quasi-static (EQS) regime. To mitigate interference effects, existing transceivers employ narrowband operation with conservative carrier-to-data-rate ratios. This paper presents an interference-aware adaptive frequency hopping (AFH) human body communication (HBC) transceiver operating below 10 MHz, where AFH is realized as interference-driven adaptive channel selection. The proposed AFH on-off keying (OOK) transceiver integrates a tiny on-chip microcontroller unit (MCU) enabling autonomous frequency hopping control, real-time channel assessment, and direct sensor interfacing. Fabricated in 65-nm CMOS occupying 0.117 mm2, the transceiver achieves 22-360 kbps data rates, -33 dB signal-to-interference ratio (SIR) tolerance at bit error rate (BER) of 10 ${}^{-3}$ , and 40 $\times$ BER improvement over single-frequency operation at maximum body distance of 180 cm. The transceiver achieves 62.2-79.5 pJ/bit energy efficiency, enabling extended battery life for distributed wearable applications, while benefiting from the inherent security of the sub-10 MHz EQS regime.