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Codiode/Problems/Sequential Logic

Johnson Counter: State Count Efficiency Comparison

MediumLogic CircuitAnalyze

Hardware designers must balance flip-flop count against decoding logic complexity when selecting a counter architecture for timing generation. The system under analysis evaluates three distinct N-bit counter topologies: a Ring counter, a Johnson counter, and a standard Binary counter.

For a baseline configuration of N = 8 flip-flops, each architecture yields a vastly different number of valid states and requires different combinational overhead to decode those states. Determine the state efficiency, defined strictly as the ratio of valid states to the number of flip-flops, for each architecture. Analyze the hardware trade-offs required to decode a specific 16-state sequence using either a Johnson counter or a standard binary counter.

Constraints

  • Assume standard D-type flip-flops for all architectures.
  • State efficiency is defined as the total number of valid states divided by N.
  • Decoding logic cost is evaluated based on the number of inputs per AND gate required to decode a single unique state.

Topics

sequential-logiccountersstate-machinejohnson-counter

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