Wireless power transfer for implantable medical devices using piecewise resonance to achieve high peak-to-average power ratio

Wireless power transfer is emerging as the pre-eminent powering technology for implantable medical devices. Efficiency, simplicity, and reliability are the key goals for receivers in vivo. We use piecewise resonant wireless power transfer (PR-WPT) to achieve these goals. A high peak-to-average power ratio (PAPR) waveform is generated by a current-mode class D amplifier operating at 6.78 MHz. A 4
^th
-order passive filter is matched to the fundamental and third harmonic voltages of the transmitter, using harmonic elimination for the waveform and closed-form impedance analysis. A full-bridge Schottky rectifier converts the matched voltage into dc. Experiment demonstrates the proof of principle and simulation results show that the piecewise resonant methods can increase the dc output voltage by up to 30%, hence improving the rectifier efficiency. Potential applications for PR-WPT systems are discussed.