| 摘要 |
PURPOSE:To reduce the fact that an output dynamic range of a differential amplifying circuit is limited by the minimum potential of a signal in the base of the fourth transistor, by making a part or the whole of a current of the first constant-current flow through the fifth transistor, when a signal of the fourth transistor is outputted. CONSTITUTION:When supply voltage is not applied to the second supply voltage supply terminal 14, a signal S1 is outputted to an output terminal 13, and when supply voltage is applied to the second supply voltage supply terminal 14, a signal S2 is outputted to the output terminal 13. When the signal S1 is outputted, the fifth transistor 15 is cut off, therefore, the operation is all the same as that of a conventional device. On the other hand, when the signal S2 is outputted, a part or the whole of a current of the first constant-current source 3 flows through the fifth transistor 15, therefore, the maximum potential of the base of the third transistor 10a is lowered by a voltage drop portion of a load resistor 4 by a current flowing through the fifth transistor 15 in comparison with a conventional device. Accordingly, an output dynamic range of a differential amplifying circuit 5 can be widened by its portion. |
