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Codiode/Problems/Sequential Logic

4-Bit Ripple Counter: Propagation Stagger

MediumLogic CircuitTiming Diagram

A 4-bit asynchronous ripple up-counter is built from negative-edge-triggered flip-flops where each stage has a propagation delay of exactly one time step.

Five signals are shown: CLK (clock, period 8), Q0 (LSB output), Q1 (output), Q2 (output), and Q3 (MSB output). The counter initially holds the binary value 0111, meaning Q0=1, Q1=1, Q2=1, and Q3=0.

Trace Q0, Q1, Q2, and Q3 across all 16 time steps.

Constraints

  • Apply exactly one time step of delay for every triggered output transition.
  • A stage only toggles when its specific clock input experiences a HIGH-to-LOW transition.
  • Subsequent stages are clocked by the output of the preceding stage, not by the main CLK.

Topics

Timing AnalysisCountersPropagation Delay

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