A novel switched-capacitor based partial power architecture for a 20 MHz resonant SEPIC

This paper presents a new switched-capacitor (SC) based partial power architecture which enhances the performance of resonant dc-dc converters operating at high frequency (HF, 3 MHz-30 MHz) and very high frequency (VHF, above 30 MHz). A wider input and output range, larger voltage conversion ratio, smaller size and excellent transient performance are expected. The prototype comprises of a 20MHz resonant single-ended-primary-inductor-converter (SEPIC) as a regulated stage and a high-efficiency (96.5 %) 200 kHz SC as an unregulated stage. The resonant SEPIC handles 30 % of total the input power while regulates the output using a high bandwidth (170 kHz) ON/OFF PWM control scheme, which enables fast transient responses. The high-efficiency SC processes 70 % of the input power and provides a large voltage conversion ratio. The low energy storage requirements of the proposed converters allow the use of air-core inductors and ceramic capacitors, thereby eliminating magnetic core loss, and short-lived electrolytic capacitors. The power stage of the prototype achieves a peak efficiency of 93.7 % and a power density of 705.86 W/in³ at 93.88 W.