Ripple counter fault analysis In a 4-bit ripple counter, the second flip-flop has failed and is locked (stuck) so it no longer toggles. What will happen to the third and fourth stages of the chain?

Introduction / Context:
Ripple counters rely on a chain where each flip-flop’s output clocks the next stage. Understanding failure effects is useful for troubleshooting. If a stage becomes stuck and ceases to toggle, the fate of subsequent stages depends on how they receive their clocks.

Given Data / Assumptions:

• We have a standard ripple (asynchronous) counter.
• The second flip-flop’s Q output is the clock source for the third stage.
• “Locked up” means the second stage Q no longer provides transitions.

Concept / Approach:
In a ripple design, stage n+1 toggles only when stage n changes state. If stage n stops toggling, it stops delivering clock edges downstream. Without edges, subsequent stages cannot transition and their counts freeze at whatever state they were last in.

Step-by-Step Solution:
Identify the clock path: CLK3 comes from Q2; CLK4 comes from Q3.Second stage locked → no rising/falling edges on Q2.No edges on Q2 → third stage receives no clock → Q3 remains constant.No edges on Q3 → fourth stage receives no clock → Q4 remains constant.

Verification / Alternative check:
A timing diagram with Q2 stuck shows Q3 and Q4 flatlined. In-circuit observation with a scope would reveal no transitions downstream.

Why Other Options Are Wrong:
“Continue to count” is impossible without clock edges. “Incorrect outputs” implies activity; with no clocks there is none. “Molten silicon” is humorous but not an engineering outcome.

Common Pitfalls:
Confusing ripple with synchronous counters (which share a common clock); in synchronous designs, a single stage failure may not block the clock to others.

Final Answer:
stop counting