Operational amplifier having stable operations for a wide range of source voltage, and current detector circuit employing a small number of elements

摘要

An operational amplifier has a differential amplification section, an output section, a control signal generation unit, and a drive control unit. The output section has a first transistor of a first conductivity type and a second transistor of a second conductivity type that is opposite to the first conductivity type. The first and second transistors are connected in series between a first power source unit and a second power source unit, and the first transistor is driven according to an output of the differential amplification section. The control signal generation unit is used to detect a current flowing through the first transistor and generate a control signal in response to the detected current. The drive control unit is used to drive the second transistor in response to the control signal.