An Inductive Voltage/Current-Mode Integrated Power Management with Seamless Mode Transition and Energy Recycling.

An integrated power management (IPM) with the unique capabilities of seamless-voltage/current-mode (SVCM) operation and energy recycling is presented for robust inductive power delivery. Utilizing parasitic bulk diodes with lower voltage drop, this IPM seamlessly transitions between voltage mode (VM) and current mode (CM) in a safe and robust fashion, extending the input-voltage range (removing dead zone) and significantly improving power-conversion efficiency (PCE) in CM operation. The IPM first provides the required load power (P) by one-step rectification/regulation, and then stores the surplus energy into a storage capacitor to extend the receiver (Rx) operation time via energy recycling when the input power is insufficient. The theory behind the energy recycling is presented. A proof-of-concept chip was fabricated in a 0.35 µm CMOS process. In measurements, the chip safely achieved a regulated voltage of 3 V for a wide input-voltage range (without dead zone) by switching the Rx LC-tank at 142 kHz. With zero input power, the chip extended the Rx operation time by 250% thanks to the energy recycling.