The purpose of this paper is to demonstrate a systematic approach to design high-performance bootstrap gate drive circuits for high-frequency, high-power, and high-efficiency switching applications using a power MOSFET and IGBT. It should be of interest to power electronics engineers at all levels of experience. In the most of switching applications, efficiency focuses on switching losses that are mainly dependent on switching speed. Therefore, the switching characteristices are very important in most of the high-power switching applications presented in this paper.
One of the most widely used methods to supply power to the high-side gate drive circuitry of the high-voltage gate-drive IC is the bootstrap power supply. This bootstrap power supply technique has the advantage of being simple and low cost. However, it has some limitations, on time of duty-cycle is limited by the requirement to refresh the charge in the bootstrap capacitor and serious problems occur when the negative voltage is presented at the source of the switching device. The most popular bootstrap circuit solutions are analyzed; including the effects of parasitic elements, the bootstrap resistor, and capacitor; on the charge of the floating supply application.