Characterization of IGBTs for high-speed switches for laser applications

This paper presents a characterization strategy and a special gate driving method for IGBT devices to use them in laser applications. The gate driving method can be used for any MOS-controlled device e.g. MOSFETs. Starting from a real laser circuit the required parameters for a single device are derived. A scaled circuit which follows from an equivalent energies approach is presented to investigate a single device. The gate drive strategy, called Gate Boosting, uses an elevated gate voltage along with a special timing for switching to increase the speed. Measurements on various IGBT-chips show that it is possible to increase the peak current and the current and voltage slope by a factor of 2 to 4 compared with a conventional gate drive strategy. So, the range of pulsed power applications with IGBTs is extended. The obtained dynamics are promising for a cascade of IGBTs to drive a nitrogen gas laser. Special attention is paid to the switching and conduction losses of the devices. Both types of losses are measured and verified.