125 kHz Wireless Energy and 25 kbps Data Transfer for Wearable Device

This paper presents a 125 kHz wireless energy and 25 kbps data transfer system for a wearable device. In this system, the wireless transfer link is through a coupled transformer. The model of a coupled transformer is discussed, and the mismatch between measured and simulated coupling value is within 3 %. For a wearable scenario, the coupled transformer is designed to fit the bending degree of the wrist. The designed transformer achieves a best coupling factor of 0.42 with ±15mm displacement tolerance. The wireless data link can support 25 kbps data transfer in ASK modulation, and the system wireless power transfer link achieves a 40% efficiency in the optimized position, which fits the application requirement.