Amplifier circuit having two negative feedback circuits

摘要

The input stage of an amplifier circuit formed from first and second semiconductor differential amplifiers comprising a pair of transistors having emitter electrodes connected to each other, respectively. The respective collector electrodes of one pair of transistors in each of the first and second semiconductor differential amplifiers is connected to the respective collector electrodes of the other pair of transistors, the base electrode of one transistor of each pair of transistors respectively being connected to an input terminal of the amplifier circuit and the base electrode of the other transistor of each pair of transistors respectively being connected to first and second negative feedback circuits connected to the output stage of the amplification circuit. First and second electrical switches are respectively connected to the common emitter electrodes of each pair of transistors. One of the first and second electrical switches is controlled to be closed selectively.