| 摘要 |
PURPOSE:To prevent a decrease in noise margin by connecting a resistance in series to a collector load resistance on the side where an emitter follower performing wired OR logical operation is connected. CONSTITUTION:Switching logical circuits 1 and 2 consists of transistors TRQ1i, TRQ2i, and TRQ3i whose emitters are connected in common, a constant current source Isi, load resistances R1i and R2i, and emitter followers TRQ4i and TRQ5i. Then, a resistance RA is connected in series to a collector load resistance R2 on the side where an emitter follower performing wired OR logical operation is connected. The value of the resistance RA is so set that the decrement of the base-emitter voltage VBE of a TRQ4 when the product of a constant current IS and the resistance value is a half as much as the operating current of the TRQ4 is compenstated. Consequently, when an output terminal Z connected to the emitter common terminal of the TRQ5 is at a low potential, a noise margin is increased. |
