A method of forming a semiconductor device includes a GaN FET with an overvoltage clamping component electrically coupled to a drain node of the GaN FET and coupled in series to a voltage dropping component. The voltage dropping component is electrically coupled to a terminal which provides an off-state bias for the GaN FET. The overvoltage clamping component has a breakdown voltage less than a breakdown voltage of the GaN FET. The voltage dropping component is formed to provide a voltage drop which increases as current from the overvoltage clamping component increases. The semiconductor device is configured to turn on the GaN FET when the voltage drop across the voltage dropping component reaches a threshold value.