Functionally comparing SR and JK flip-flops, which distinctive capability of the JK flip-flop resolves the SR invalid input and enables robust toggling behavior?
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AJK flip-flop has a feed back path
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BJK flip-flop accepts both inputs 1
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CJK flip-flop is faster than SR flip-flop
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DJK flip-flop does not require external clock
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ENone of the above
Answer
Correct Answer: JK flip-flop accepts both inputs 1
Explanation
Introduction / Context:SR and JK flip-flops are foundational sequential elements. The SR latch/flip-flop has an invalid input condition when S=R=1. The JK flip-flop modifies the topology to eliminate this invalid state and provide a predictable toggle behavior when both inputs are asserted.
Given Data / Assumptions:
- SR invalid state occurs at S=R=1.
- JK inputs are analogous to S and R, named J and K.
- Edge-triggered variants are typical in synchronous design.
Concept / Approach:In a JK flip-flop, when J=K=1 at the active clock edge, the output toggles (Q(next) = NOT Q). This replaces the SR undefined condition with a well-defined transition, thanks to internal feedback and gating arrangements.
Step-by-Step Solution:
Identify SR limitation: S=R=1 → invalid/forbidden.Identify JK behavior: J=K=1 → toggle event on clock.Conclude the distinctive capability: accepting both inputs high safely and deterministically.Verification / Alternative check:JK truth tables show four modes: hold (00), reset (01), set (10), toggle (11). This confirms the resolution of the SR forbid state.
Why Other Options Are Wrong:
- has a feed back path: true but not the key distinguishing functional capability asked.
- is faster: speed depends on implementation; not a defining functional difference.
- does not require external clock: false for synchronous JK flip-flops; latches differ.
- None of the above: incorrect because accepting both 1s is the core difference.
Common Pitfalls:Confusing level-sensitive latches with edge-triggered flip-flops, and thinking feedback alone defines the difference rather than the resulting toggle mode.
Final Answer:JK flip-flop accepts both inputs 1