JPS6410709A - Operational amplifier - Google Patents

Abstract

PURPOSE:To provide an operational amplifier with a power-down function without spoiling a gain or a distortion characteristic by providing a transistor(TR), which receives a power-down control signal, and biases the TR of an output circuit into a non-conductive state. CONSTITUTION:A bias voltage is supplied by a bias voltage generation circuit 3, which stops generating the bias voltage by the power-down control signal 11, to a differential amplification circuit 4 and to a level shift circuit 5, which shifts the level of output of the differential amplification circuit 4 and supplies it to the output circuit 6. Then, the TR M20, which comes to off state by the power-down control signal 11, is inserted in the level shift circuit 5, and the TRs M21, M22, which turn the TRs M8, M9 of the output circuit 6 into OFF similarly, are provided. Thus, an operational amplifier with the power-down function can be obtained without spoiling the symmetry property of the output circuit 6.