A 92.7%-Efficiency 6.78-MHz Energy-Resuscitating Resonant Regulating Rectifier With Dual Outputs for Wirelessly Powered Devices

This article presents an energy-resuscitating resonant regulating rectifier (ER4) for wireless power transfer (WPT) systems. ER4 can convert the energy that would otherwise be wasted in conventional regulating rectifiers to generate an additional regulated output voltage. The ER4 system regulates and provides two different output voltages without the need for low dropout regulators thanks to the proposed dual-output comparator. This comparator can efficiently generate two gate control signals for regulating dual-output voltages, maximizing power conversion efficiency (PCE). In addition, the dual-output comparator adopts a pulsewidth memorizer (PWMem), a current replica, and a current bleeding technique to prevent incident high-surge back current. The 0.77-mm²0.18μ m CMOS ER4, which was also equipped with back/forward data telemetry functions, verified that the secondary regulation voltage can be generated in a wide range from 1 to 4.5 V while maintaining the first regulation voltage at 4.5 V at the carrier frequency of 6.78 MHz. The peak PCE of 92.74% was achieved with the output power of 107.5 mW. Moreover, the ER4 system is the first to incorporate the data telemetry with a bit error rate (BER) of less than 10^-6 while simultaneously regulating two output voltages.