IEEE/ANSI logic symbol notation — meaning of an internal underlined diamond In IEEE/ANSI digital symbols, what output characteristic is indicated when a gate symbol shows an internal underlined diamond at its output?

Difficulty: Easy

Correct Answer: tristate buffers.

Explanation:


Introduction / Context:
IEEE/ANSI logic symbols add small annotations to indicate inversion, enable control, open-collector behavior, and tri-state capability. Interpreting these marks is crucial when reading schematics quickly without full textual notes.


Given Data / Assumptions:

  • The symbol includes an internal underlined diamond drawn at or near the output side.
  • We are identifying the specific output characteristic implied by this mark.


Concept / Approach:
In the IEEE/ANSI convention, an internal diamond near the output denotes special output behavior; the underlining indicates an enabling control that can place the output in a high-impedance state. Designers use this to show that the gate is capable of three states: logic HIGH, logic LOW, and Hi-Z, typically controlled by an enable pin that may be active-HIGH or active-LOW (bubble on the control pin indicates polarity).


Step-by-Step Solution:

Locate the internal diamond at the output → indicates special output stage.Underlined annotation → relates to controlled output state.Map to known IEEE/ANSI practice → tri-state capability (Hi-Z).Therefore select “tristate buffers.”


Verification / Alternative check:
Consult IEEE/ANSI logic symbol guides used in textbooks and EDA tools; tri-state outputs are commonly indicated with distinctive internal marks.


Why Other Options Are Wrong:

  • A: Totem-pole is a physical output structure, not uniquely identified by the underlined diamond.
  • B: Open-collector is usually indicated by a different annotation (collector output mark), not this symbol.
  • C: Quadrature amplifiers are analog and unrelated to digital output annotations.


Common Pitfalls:
Confusing inversion bubbles (polarity) with special output-state indicators; bubbles indicate active-LOW, not tri-state behavior.


Final Answer:
tristate buffers.

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