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Flip-Flops - Technical MCQs

Q1:

A positive edge-triggered J-K flip-flop is used to produce a two-phase clock. However, when the circuit is operated it produces erratic results. Close examination with a scope reveals the presence of glitches. What causes the glitches, and how might the problem be corrected?

A The PRESET and CLEAR terminals may have been left floating; they should be properly terminated if not being used.

B The problem is caused by a race condition between the J and K inputs; an inverter should be inserted in one of the terminals to correct the problem.

C
A race condition exists between the Q and Q outputs to the AND gate; the AND gate should be replaced with a NAND gate.

D
A race condition exists between the clock and the outputs of the flip-flop feeding the AND gate; replace the flip-flop with a negative edge-triggered J-K Flip-Flop.

ANS:D -

A race condition exists between the clock and the outputs of the flip-flop feeding the AND gate; replace the flip-flop with a negative edge-triggered J-K Flip-Flop.


Invertor logic is : f = not(A).

So NOT gate Acts as an Invertor.