Applications and characterization of four quadrant GaN switch

Bi-directional switches, also called four quadrant switches (FQS), are the basic building blocks in many power converter circuits, such as cyclo-converters, matrix converters etc. Conventional approaches to realize bi-directional switch involves combination of unidirectional controllable blocking device (IGBT or MOSFET) and diode. In this approach, current flows through multiple devices for any direction of current flow. This leads to higher conduction losses. Moreover, use of multiple devices increases system size. The die size and semiconductor losses can be reduced by realizing a bi-directional switch using a single die. Further improvement can be achieved by using Gallium Nitride (GaN) semiconductor. This paper discusses characterization of such a four quadrant GaN switch, made using a single die. Static characterization is performed, where the on-state resistances are obtained along with the output characteristics. A double pulse test setup has been built for characterizing FQS's and the experiments were performed to obtain the turn-on and turn-off switching energies.