| 摘要 |
PURPOSE:To eliminate an adjusting element of a collector side of a differential transistor (Tr) by providing a buffer circuit comprising an emitter follower to a pre-stage of the differential Tr, dividing a resistor bypassing the circuit and connecting in parallel with the adjusting element such as a fuse to each resistor. CONSTITUTION:The emitter follower EF1 comprising a TrQe1 and a constant current source I1 and the emitter follower EF2 comprising a TrQe1 and a constant current source I2 are connected in cascade with the pre-stage of the differential transistor (hereinafter Tr) of the differential amplifier stage 1. Then the constant current source I1 is biased by a bias circuit 2a comprising a power voltage Vcc, a TrQz and a resistor Rz. Since the TrQz and a TrQx constitute a current mirror circuit, a current the same value as that of a current flowing to the circuit 2a flows into the emitter follower EF1. Fuses F1, F2 are inserted in parallel with the resistor Rz in the circuit 2a and the resistor is formed adjustably. |
