Patent ID: 8319529

Claim:
A resonant gate drive circuit for a voltage controlled transistor which is driven according to a voltage applied to a gate, comprising: a first switching element and a second switching element connected to a drive circuit power source in series, which are controlled according to a control signal; a resonant inductor connected to a junction of the first switching element and the second switching element; a resistor connected to the other terminal of the resonant inductor which is not connected to the first and second switching elements; and a voltage controlled transistor connected to the resistor in a gate; wherein the voltage controlled transistor is of a normally-on type, a capacitor is provided with one electrode connected to a gate of the normally-on voltage controlled transistor and the other electrode connected to the resistor, and a third diode is provided with an anode connected to the gate of the normally-on voltage controlled transistor and a cathode of the third diode connected to a source of the normally-on voltage controlled transistor.