| 摘要 |
PURPOSE: A low power output circuit is provided to reduce current consumption and to optimize output characteristics by replacing a resistor in an emitter follower with a transistor. CONSTITUTION: A low power output circuit includes a differential amplifier(11) and an emitter follower(12). The differential amplifier(11) includes bias resistors and transistors having a bias current varied according to an input voltage. The emitter follower(12) is connected to an output terminal of the differential amplifier and includes a transistor for output bias. The differential amplifier(11) includes a first resistor(Q1) receiving the input voltage, a second transistor(Q2) receiving a reference voltage, first through third emitter resistors(Re1,Re2,Re3) connected between emitters of the transistors(Q1,Q2) and a ground potential, third transistor(Q3), a first collector resistor(Rc1) between the first transistor(Q1) and a source voltage, and a second collector resistor(Rc2) between the second transistor(Q2) and the source voltage. The emitter follow includes fourth and fifth transistors(Q4,Q5). The fourth transistor(Q4) includes a base connected to a collector of the first transistor(Q1) and a collector connected to the source voltage. The fifth transistor(Q5) includes a base connected between the first and second emitter resistors(Re1,Re2), a collector connected to an emitter of the fourth transistor(Q4), and an emitter connected to the ground potential.
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