Ryota Shinoda, Kazutoshi Tomita, Yuya Hasegawa, and Hiroki Ishikuro, "Voltage-Boosting Wireless Power Delivery System With Fast Load Tracker by ΔΣ-Modulated Sub-Harmonic Resonant Switching,"at 2012 IEEE International Solid-State Circuits Conference (ISSCC), San Francisco, USA, Feb. 22, 2012.