Abstract: This paper proposes a driving circuit for IGBTs with long duration gating signals output, by which only narrow pulses are transferred by the high-voltage isolation pulse transformer and no high-voltage isolation DC power supplies are utilized. Narrow positive pulse "turn-on" and negative pulse "turn-off" are both transferred by the pulse transformer which is smaller and lighter, comparing with that transferring long duration gating signals. The pulse width broadening circuit turns the IGBTs on at the rising edge of "turn-on" pulse and turns the IGBTs off at the rising edge of "turn-off" pulse, and it also stores energy from "turn-on" pulse, without high-voltage isolation DC power supplies. Narrow pulses generator and over-current protection circuit are interactively designed to produce negative voltage pulse on the gate of IGBTs, which reduces the turn off transition period and enhances the turn off reliability, whether the IGBTs are normally turned off or closed due to over-current protection. The proposed driving circuit is applied to the cascaded high-voltage Marx generator, and the pulse widths of "turn-on" and "turn-off" pulses are both 2 μs. Experimental results show that the Marx generator functions well with maximum voltage output of 20 kV and pulse width at 3.5~50 μs. When arcing generates at plasma load, the over-current protection circuit reacts quickly to turn off the IGBTs with high reliability. The performance of the driving circuit proves its capability of producing long duration gating signals for IGBTs with high reliability and practical validity.