PURPOSE: To quickly restore the normal operating state from an overexcitation state with a small number of constituting parts by providing three diodes and a current source which biases diodes in the overexcitation state.
CONSTITUTION: Half-amplifiers 22 and 24 are provided which include feedback transistors TRs Q5 and Q6 which drive a common load impedance and supply a differential output current. The half-amplifier 22 is provided with a first feedback line capable of operation in the normal operating state and a second feedback line capable of operation in the overexcitation state. The first feedback line has diodes D1 and D5 connected to the feedback TR Q5, and the connection point between diodes is connected to a common load impedance R1. Since the second feedback line includes a diode D3 connected to the feedback TR Q5, the differential amplifier and feedback TRs keep the operation during the overexcitation state and are separated from the load impedance R1. When the over-excitation state is released, the first feedback line is set to the operating state again to immediately restore the normal operating state.
DABORIN FUANDATSUKU
FURANKU JII DEIJIOBANNI
