In addition, at the time moment t12, when the switching element Q1 transitions from off to on, a part of the power charged in the capacitor C1 is consumed by the drive circuit DRV1, and the voltage potential V(N4) of the node N4 slightly decreases. The consumed power is charged by the current Id1a flowing from the DC voltage source E1 to the capacitor C1 when the switching elements Q1 and Q2 are turned on. As a result, the voltage V(N4) at the node N4 reaches high again.

Also at the time moment t14, when the switching element Q1 transitions from on to off, a part of the power charged in the capacitor C1 is consumed by the drive circuit DRV1, and the voltage potential V(N4) of the node N4 slightly decreases. The consumed power is charged by the current Ic1b flowing from the terminal P1 to the capacitor C1 when the switching elements Q1 and Q2 are turned off. As a result, the voltage V(N4) at the node N4 reaches high again.

Modified Embodiments of First Embodiment