| 摘要 |
PURPOSE:To prevent droppage of efficiency during low speed operation of a motor by providing a square pulse train complimentarily to first and second circuits according to whether an input signal exists or not thereby changing the polarity of gate voltage reliably and carrying out ON-OFF operation. CONSTITUTION:A high frequency pulse train fc from a high frequency pulse train generator 51 and an input signal SG to an input signal terminal 52 are fed to gate circuits 53, 54, which carry out complementary operation corresponding to the input signal SG. When a bipole square wave pulse train P1 is fed to the primary winding 32 of the transformer 31 in a first circuit 30, a square wave corresponding to the bipole square wave pulse train P1 is produced in the secondary winding 33, then it is full-wave rectified through diodes 35, 35 to produce a rectified output e1 which is applied onto the gate G of a power MOS-FET 20 thus conducting the MOS-FET 20. |
