A Review of Integrated Circuits for Resonant Wireless Power Transfer in Biomedical Implants

This paper reviews recent advances in integrated circuits for resonant wireless power transfer (WPT) systems in biomedical implants, with emphasis on resonant compensation networks and receiver-side power conversion. In these systems, a compact receiver coil must harvest attenuated alternating current (AC) power through biological tissue and convert it into a safe, efficient, and regulated direct current (DC) supply for implantable electronics. Limited coil size, weak coupling, load variation, and thermal safety constraints have driven the evolution from passive rectifiers to active and regulated rectifiers with delay-compensation techniques. This review first introduces the operating principles of resonant WPT links and compares series–series, series–parallel, parallel–series, and parallel–parallel compensation topologies in terms of output characteristics and implant suitability. It then summarizes passive, cross-coupled, active full-wave, delay-compensated, and regulated rectifiers. Finally, design guidelines are provided for selecting compensation and rectifier architectures according to power level, coupling condition, operating frequency, integration complexity, and regulation requirements.