| 摘要 |
PURPOSE:To make it possible to adjust logical amplitude by obtaining the sum of a current-source current and control current with a control terminal held at a high level or only the current-source current at a low level. CONSTITUTION:When control terminal 14 held at a high level, a high bias from bias circuit 17 of current-source circuit part 15 is applied to the base of transistor TrQ3, which conducts a load current, the sum of a current from current source 4 and a control current, thereby increasing logical amplitude. When terminal 14 is held at a low level or open, on the other hand, circuit 17 applies a low bias to the base of TrQ3, which puts in an OFF state, so that the logical amplitude will be adjusted only by the value of the current of current source 4 to normal one. Consequently, changing the state of terminal 14 attains adjustments of the logical amplitude. |
