One of the major drawbacks to the use of asynchronous counters is:
Options
A. low-frequency applications are limited because of internal propagation delays
B. high-frequency applications are limited because of internal propagation delays
C. asynchronous counters do not have major drawbacks and are suitable for use in high- and low-frequency counting applications
D. asynchronous counters do not have propagation delays and this limits their use in high-frequency applications
Correct Answer
high-frequency applications are limited because of internal propagation delays
More questions
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.
Correct Answer: 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.