for making a freewheeling current flow to power source v a or ground terminal o can also be used instead of freewheeling diodes d f1 and d f2 although switches a r a f a a and a g are denoted as mosfets in fig4 they can be any switching elements so long as they perform the same or similar functions preferably switches a r a f a a and a g have a body diode such as a pn junction separated structure of semiconductor ics in resonance circuit 112 inductor l is coupled to parasitic inductor l p1 and freewheeling diode d f1 is coupled between inductor l and power source v a and freewheeling diode d f2 is coupled between inductor l and ground terminal o respectively switches a r and a f are coupled in parallel between inductor l and capacitor c r capacitor c r being coupled to ground terminal o capacitor c r acts as a power source for supplying voltage v a 2 that amounts to approximately half address voltage v a additionally diodes d 1 and d 2 for interrupting a current flowing to the body diode of switches a r and a f can be formed between inductor l and capacitor c r switches a r and a f act as means for charging and discharging panel capacitors c p1 and c p2 in output circuit 114 switches a a and a g are coupled in series between power source v a and ground terminal o and their.