An electronic device includes a first group III nitride transistor and an over current protection circuit (OCP). The OCP circuit includes an input device and a detection device. The input device is configured to receive a control signal and to generate a first voltage to a gate of the first group III nitride transistor. The detection device is configured to generate an output signal having a first logical value if a current at a drain of the first group III nitride transistor is less than a predetermined value and to generate the output signal having a second logical value if the current at the drain of the first group III nitride transistor is equal to or greater than the predetermined value, wherein the first logical value is different from the second logical value.