Case Study: National Cheng Kung University achieves 76% wireless Li‑ion charging efficiency with Keysight ADS

NCK University Uses ADS to Create an Impedance Matching Method for Wireless Battery Charging

National Cheng Kung University (NCKU) needed to wirelessly recharge a 10‑mAh Li‑ion implantable battery within five hours, but impedance matching was difficult because the battery’s resistance, reactance, and voltage change with state-of-charge and the system had tight MICS‑band and size constraints. NCKU used Keysight’s Advanced Design System (ADS) to explore and develop a practical matching approach.

Using Keysight ADS, researchers simulated a dual‑diode rectifier with harmonic‑balance analysis, applied a sweeping method to match the rectenna to the dynamic Li‑ion load, and performed EM‑circuit co‑simulation to optimize the rectenna and matching network. The Keysight‑enabled design produced a 76% RF‑to‑DC conversion efficiency over a five‑hour charge cycle at 10 dBm input, compared with roughly 50% in comparable prior work.

National Cheng Kung University