Building high-frequency high-voltage switching converters for renewable energy systems

This paper presents various circuit techniques and design considerations for high-voltage integrated switching converters to enable their high-frequency operation, thereby minimizing the converter cost, weight and volume. First, the design considerations of realizing a low-power and high-speed synchronous gate driver for power FETs are explained in order to allow the power converter operating in the MHz range with negligible power efficiency degradation. The high-speed high-accuracy high-voltage sense-FET based current sensor to monitor the peak inductor current is also discussed. To demonstrate above circuit techniques, a 40-V 9.6-W buck converter is implemented in a high-voltage 0.35-μm CMOS process with dual on-chip power nFETs. The proposed converter can operate at 2 MHz. The peak power efficiency of the proposed converter is 93%, while the converter can still provide >90% efficiency under the full-load of 9.6 W at 2 MHz.