Mitigation of Common Return Path in Wearable Galvanic Coupled Intrabody Communication

This study explores strategies for suppressing common ground return path in wearable galvanic coupled (GC) intrabody communication (IBC) systems. Specifically, it assesses the effectiveness of two isolation methods - an isolation transformer (balun) and an optocoupler - in minimizing such noise. Three system configurations were analyzed: balun-isolated, optocouplerisolated, and non-isolated. The comparative evaluation results focused on IBC channel gain. Findings indicated that while the balun configuration effectively reduced electromagnetic interference (EMI), it also introduced signal attenuation. In contrast, the non-isolated setup, the configuration where the baluns didn't plugged to both transmitter and receiver side, demonstrated up to 30 dB higher gain at 1 MHz, underscoring a trade-off between noise suppression and signal strength. However, the non-isolated setup exploits a low-impedance ground return, bypassing the body channel and inflating gain; it's included for comparison purposes as it's incompatible with IBC systems. Additionally, the effectiveness of 50 Hz EMI suppression was examined to validate its role in mitigating power line noise.