The dual-gate W-switched power MOSFET: a new concept for improving light load efficiency in DC/DC converters

A merged dual-gate power MOSFET is described which greatly improves the light-load energy efficiency of high-speed (f>1 MHz) low-voltage DC/DC conversion by dynamically reducing input capacitance and gate drive losses during low-current load conditions. The W-switched MOSFET concept is experimentally verified using a TrenchFET employing a 30/spl times/ reduction in input capacitance during light load. Efficiency improvements better than 25% and a decade increase in useable load current were confirmed for a 1-cell Li ion to 5 V boost converter, without adversely affecting the converter's transient response. Various figure-of-merits for W-switched MOSFETs are also proposed to analyze the limits of W-switching.