PURPOSE: To obtain a comparator, an A/D converter, a PWM signal generator, a power source device and a power source controller which have high speed and high performance and are capable of miniaturizing chips when they are incorporated into IC chips.

CONSTITUTION: A D/A converter 21a is operated by a time division and required comparison reference voltage is supplied to chopper type comparators 5-1 and 5-2. The timing of the operation is mutually shifted by each chopper type comparator, in such a manner that comparison reference voltage is charged in an input capacitor 23a by the chopper type comparator 5-2 when a comparsion operation is performed in the chopper type comparator 5-1. Thus, a comparison can be performed at a high speed without lowering accuracy.