The circuit given below has no output on Q1 when examined with an oscilloscope.

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Question
The circuit given below has no output on Q₁when examined with an oscilloscope. All J-K inputs are HIGH, the CLK signal is present, and the Q₀ is toggling. The C input of FF₁ is a constant LOW. What could be causing the problem?
Options
A. The Q₀ output should be connected to the J input of FF₁.
B. The output of FF₀ may be shorted to ground.
C. The input of FF₁ may be shorted to ground.
D. Either the output of FF₀ or the input of FF₁ may be shorted to ground.

Correct Answer

Either the output of FF₀ or the input of FF₁ may be shorted to ground.

1. 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?
Options
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.

2. What type of circuit is represented in the given figure, and which statement best describes its operation?
Options
A. It is a tristate inverter. When the ENABLE input is HIGH, the output is effectively an open circuit?it is neither LOW nor HIGH.
B. It is a programmable inverter. It can be programmed to function as either an active LOW or an active HIGH inverter.
C. It is an active LOW buffer, which can be turned on and off by the ENABLE input.
D. None of the above.

8. On a positive edge-triggered S-R flip-flop, the outputs reflect the input condition when ________.
Options
A. the clock pulse is LOW
B. the clock pulse is HIGH
C. the clock pulse transitions from LOW to HIGH
D. the clock pulse transitions from HIGH to LOW

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