Patent attributes
Circuits and devices are provided for reliably holding a normally-off Gallium Nitride (GaN) power transistor, such as a Gate Injection Transistor (GIT), in a non-conducting state when a gate of the power transistor is not driven with an active (turn-on) control signal. This is accomplished by coupling a normally-on pulldown transistor between the gate and the source of the power transistor, such that the pulldown transistor shorts the gate to the source when the power transistor is not set for its conducting state. The pulldown transistor is preferably located on the same semiconductor die as, and in close proximity to, the power transistor, so as to avoid spurious noise at the power transistor gate that may unintentionally turn on the power transistor. A pulldown control circuit is coupled to the gate of the pulldown transistor and autonomously turns off the pulldown transistor when the power transistor is set to conduct.
