Abstract: A differential amplifier includes an input stage for receiving input signals, an output stage for generating output signals, and an attenuating circuit for attenuating the output signals and feeding attenuation signals back to the input stage. The input stage includes a current switch formed by two transistors connected commonly to a current source and each connected to two load amplifiers. The load amplifiers are controlled by the attenuation signal, to substantially reduce the amplification of the two transistors.

Abstract: A current switching circuit has a setting section, a switching section and a switch changeover section. The switching section has a current mirror circuit, n switching transistors, and a compensating circuit. The current mirror circuit has first through third transistors. Emitters of the first and second transistors are connected to a power supply terminal and bases thereof are connected with each other. The third transistor has an emitter connected to the bases of the first and second transistors, a collector grounded, and a base connected to a collector of the first transistor. The switching transistors have emitters connected to the collector of the second transistor, and collectors connected to one terminals of n load elements. The other terminals of the load elements are grounded. The switch changeover section controls the base currents of the switching transistors. The compensating circuit comprises two compensating transistors.