A circuit includes a power supply voltage node having a power supply voltage level, a protection circuit that generates a first signal having first and second logical voltage levels based on the power supply voltage level, and a gate driver. The gate driver includes a first n-type HEMT between the power supply voltage node and a first node, a second n-type HEMT between the first node and a power supply reference node, and a DCFL circuit between the first node and an output terminal. A gate of the first n-type HEMT receives the first signal, a gate of the second n-type HEMT receives a second signal, and the DCFL circuit generates a third signal at the output terminal based on the second signal when the first signal has the first logical voltage level, and as a DC voltage level when the first signal has the second logical voltage level.