Digital Logic Flashcards
7 cards from real GATE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Digital Logic flashcards as text
What is the output of the Boolean expression F = A·(A+B)?
Answer: A
By absorption law, A·(A+B) = A.
A D flip-flop stores the value of D on which edge of the clock?
Answer: Rising edge
A positive-edge-triggered D flip-flop captures D on the rising (positive) edge of the clock.
How many 2-to-4 decoders (with enable) are needed to build a 4-to-16 decoder?
Answer: 5
One 2-to-4 decoder drives the enable of four 2-to-4 decoders, totaling 5 decoders.
Which Karnaugh map grouping size is NOT valid when simplifying Boolean expressions?
Answer: 3
K-map groups must be powers of 2 (1, 2, 4, 8, …); grouping 3 cells is invalid.
The complement of (A+B)·C using De Morgan's theorem is:
Answer: A'·B'+C'
Applying De Morgan's twice: [(A+B)·C]' = (A+B)' + C' = A'·B' + C'.
In a synchronous counter, all flip-flops are clocked:
Answer: Simultaneously
In a synchronous counter, all flip-flops share the same clock signal and trigger simultaneously.
Which logic family typically has the highest noise margin?
Answer: CMOS
CMOS has higher noise margins than TTL or ECL because its output swings nearly rail-to-rail.