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Important Digital Logic and Design Short Questions

Chapter: 26
Question 1:
What is the primary use of a 555 timer?
Answer: The 555 timer is used as a monostable one-shot or an astable multivibrator (oscillator), capable of continuously changing between unstable states without external triggers.
Chapter: 26
Question 2:
What is a potential timing issue in flip-flop circuits?
Answer: A timing issue arises when the output of one flip-flop is not stable during the hold time required by the next flip-flop, leading to unreliable outputs.
Chapter: 26
Question 3:
What causes clock skew in synchronous circuits?
Answer: Clock skew occurs when the same clock signal arrives at different flip-flops at different times due to propagation delays, leading to asynchronous changes in flip-flop states.
Chapter: 26
Question 4:
How can clock skew be minimized?
Answer: Clock skew can be minimized by equalizing clock delays across different parts of the circuit to ensure simultaneous clock signal arrival at all flip-flops.
Chapter: 26
Question 5:
What are race conditions in digital circuits?
Answer: Race conditions occur when multiple internal variables change due to a single input variable, causing unpredictable and erratic circuit outputs.
Chapter: 26
Question 6:
What is a ripple counter?
Answer: A ripple counter is an asynchronous counter where flip-flops are connected such that the clock signal ripples through each flip-flop, causing them to change states sequentially.
Chapter: 26
Question 7:
How does an asynchronous counter work?
Answer: In an asynchronous counter, flip-flops are triggered by the output of the preceding flip-flop, causing the state change to ripple through the sequence.
Chapter: 26
Question 8:
What is the difference between synchronous and asynchronous counters?
Answer: Synchronous counters have all flip-flops triggered simultaneously by a common clock signal, while asynchronous counters have flip-flops triggered sequentially by the output of preceding flip-flops.
Chapter: 26
Question 9:
What is the significance of propagation delay in counters?
Answer: Propagation delay affects the timing of state changes in counters, causing delays that can accumulate and affect the accuracy of high-frequency operation.
Chapter: 26
Question 10:
How does a Mod-n counter work?
Answer: A Mod-n counter counts through 'n' unique states before resetting. For example, a Mod-6 counter counts from 000 to 101 and then resets to 000.