In a power source circuit (a switching regulator), an error amplifier circuit (or an error amplifier) is an important circuit to determine the operation of a feedback circuit in the power source circuit.
The error amplifier circuit is an analog circuit which processes analog signals. The error amplifier circuit in general has a structure in which passive elements having a large area, such as a capacitor and a resistor, are connected (see Patent Document 1 and Non-Patent Document 1).