PURPOSE: To reduce the loss by the switching at output of 0V by taking out a positive output signal and a negative output signal individually, and using this as each switching signal.

CONSTITUTION: When input signals IN enter a positive and negative slicers 2 and 3, the slicer 2 and 3 outputs the positive signal and the negative signal respectively. A positive comparator 4 compares the output signal S2 of the positive slicer with the triangular wave (sawtooth wave) from a wave generator 6, and outputs OUT1. Moreover, an absolute value circuit 7 inverts the polarity of the output signal of the positive slicer 3, and the negative comparator 5 compares the output signal S7 with the sawtooth signal S1 and outputs OUT2. Next, this is input into an inverter circuit 13, and inverter output OUT can be gotten.