A Dual-Output Single-Stage Regulating Rectifier With PWM and Dual-Mode PFM Control for Wireless Powering of Biomedical Implants.

This paper presents a reconfigurable, dual-output, regulating rectifier featuring pulse width modulation (PWM) and dual-mode pulse frequency modulation (PFM) control schemes for single-stage ac-to-dc conversion to provide two independently regulated supply voltages (each in 1.5-3 V) from an input ac voltage. The dual-mode PFM controllers feature event-driven regulation as well as frequency division. The former incorporates stable, fast, digital feedback loops to adaptively adjust the driving frequency of four power transistors, M, based on the desired output power level to perform voltage regulation and deliver fast, transient, load currents. The latter sets the driving frequency of M to a user-defined fraction (1/1 ∼ 1/32) of the input frequency (1-10 MHz). The PWM controllers incorporate stable, analog, feedback loops to accurately adjust the conduction duration of M for voltage regulation and can be combined with PFM frequency division for an extended operation dynamic range. Fabricated in 0.18 μm 1P/6M CMOS, the regulating rectifier features power conversion efficiency (PCE) of >83.8% at 2 and 5 MHz, with the first output channel delivering ∼1 mW from V of 1.5 V and the second output channel delivering variable power from V of 2.5 V to a load in the range of 0.1 to 1 kΩ. Peak PCE values of 90.75% (2 MHz, 100 Ω) and 90.7% (5 MHz, 200 Ω) are also measured. The regulating rectifier is suitable for the emerging modality of capacitive wireless power transfer to biomedical implants.