Robust Wireless Power and Data Transmission System against Misalignment for Implantable Medical Devices

Implantable medical devices (IMDs) with power and data transmission (WPDT) are rapidly developing. However, they suffer from performance degradation issues due to misalignment between transmitter and receiver coils. To improve the system's robustness against misalignment, this paper develops an innovative WPDT circuit incorporating an impedance matching network (IMN) in a Class-E power amplifier (PA). Firstly, the target impedance region is identified to obtain the high-efficiency power transmission of the Class-E PA. Then, an ASK modulation scheme is implemented using MOSFETs and a data modulation inductor to transmit data. Leveraging the theoretical derivations about the target impedance region, the IMN circuit is implemented to keep impedance within the target region, avoiding performance degradation due to misalignment. Finally, the robustness proposed WPDT with an IMN circuit is validated through experiments for 10mm misalignment, demonstrating a 17% improvement in efficiency compared with a conventional WPDT system without an IMN circuit. The experiment also validates that the bit error bit, which evaluates the data transmission reliability, remains less than 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> for a 1Mbps data rate with a modulation index of 10%.