| 摘要 |
PURPOSE:To select automatically an intermediate value with a high precision, by compensating a voltage dropped between the base and the emitter of a transistor (TR). CONSTITUTION:Power sources 44-49 having the same voltage as a voltage VBE between bases and emitters of TRs 36-41 are connected base series resistances 24, 26, 28, 30, 32, and 34 and bases of TRs 36-41. When E3<E2-VBE<E1- 2VBE is true among input signals E1-E3 of terminals 21-23, TRs 36-40 are cut off, and the TR41 is made conductive. As a result, the signal E2 impressed to the collector of the TR41 is outputted to a terminal 43. When E3<E2-V0<E1- 2V0 and 0<V0<VBE are true, TRs 36-40 are saturated, and the TR41 is made conductive. The TR38 outputs a value which is obtained by subtracting the voltage VBE of the TR38 from the sum of the voltage E0 inputted to the base and the output of the power source 46, namely, the signal E2 to the emitter. As a result, the signal E2 of an intermediate value is outputted to the terminal 43 by the parallel operation of TRs 38 and 41. When E1=E2=E3 is true, all TRs are operated similarly to the TR38 to output the signal E1 as an intermediate value signal. |
