Design Considerations for a Fast Stacked-MOSFET Switch

For fast pulse generators using pulse-forming lines for energy storage, a fast MOSFET is employed as switch. It needs to have the capability of switching on the current within a short rise time. Fast switching of MOSFET requires the gate driver next to MOSFET in order to minimize the inductance. To increase the voltage switching capability of a MOSFET switch, several MOSFETs are switched in series. For such a configuration, a synchronous switching of MOSFETs is crucial. Hence, the gate drive circuitry needs to be designed to have equal propagation delay for each MOSFET. The circuitry for two stages of a stacked MOSFET switch including power supply and trigger circuit is designed, set up, and tested. The paper describes some design considerations and shows the results of some first tests.