TTL internal design: The output stage of a standard TTL logic gate uses a special push-pull arrangement commonly known as ________.
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AMultiemitter
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BTotem-pole
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CMSI
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DDIP
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EOpen-drain
Answer
Correct Answer: Totem-pole
Explanation
Introduction / Context:TTL logic families employ characteristic internal structures. Inputs often use multiemitter transistors, and outputs typically employ a push-pull stage that can both source and sink current quickly. This arrangement improves switching speed and provides stronger drive for connected loads.
Given Data / Assumptions:
- A standard (non–open-collector) TTL gate is considered.
- We are naming the output topology.
- Focus is on the common push-pull form rather than special variants.
Concept / Approach:The TTL push-pull output stage is called a totem-pole because two transistors are stacked vertically between Vcc and ground. One acts as an active pull-up for logic HIGH; the other acts as an active pull-down for logic LOW. Internal diodes or timing networks reduce shoot-through by preventing both from strongly conducting simultaneously.
Step-by-Step Solution:
Identify push-pull nature → both sourcing and sinking possible.Name of the stacked arrangement → totem-pole output.Differentiate from “open-collector,” which lacks an active pull-up.Verification / Alternative check:Review typical 7400-series internal diagrams; they show the characteristic stacked transistors in the output stage and label it as totem-pole.
Why Other Options Are Wrong:
- Multiemitter: Refers to input transistor structure, not output.
- MSI/DIP: MSI is an integration level; DIP is a package.
- Open-drain: CMOS term; TTL equivalent is open-collector, different from totem-pole.
Common Pitfalls:Confusing input architecture (multiemitter) with output topology; conflating package types with internal circuits.
Final Answer:Totem-pole