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Codiode/Problems/Sequential Logic

Ring Counter: Glitch-Free Output Property

MediumLogic CircuitAnalyze

High-speed state machines often rely on ring counters to generate multiphase control signals without combinational logic delays.

The circuit provided is a 4-bit ring counter consisting of four D flip-flops. The output of each stage feeds the directly into the input of the next stage, and the final output loops back to the first input. The active state circulates continuously through the register, transitioning sequentially through the states 1000, 0100, 0010, and 0001.

Trace the outputs Q3, Q2, Q1, and Q0 across adjacent clock cycles. Determine the transitional behavior of the individual bits and evaluate the potential for combinational glitches on the decoded output phases.

Constraints

  • The initial state is pre-loaded into the flip-flops as 1000.
  • All flip-flops share a common synchronous clock.
  • No external combinational logic is used to decode the active phase.

Topics

timingglitchescountersstate-machines

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