Johnson Counter: 8-State Sequence Trace
A 4-bit Johnson counter shifts its state on every rising edge of CLK, feeding the inverted output of the last stage (Q3_bar) into the first stage (Q0).
Six signals are shown: CLK (clock, positive-edge-triggered, period 2), Q0, Q1, Q2, Q3 (stage outputs, initially 0), and Q3_bar (inverted final stage, initially 1).
Trace Q0, Q1, Q2, Q3, and Q3_bar across all 18 time steps to complete the 8-state sequence and verify that the cycle repeats on the 9th clock edge.
Constraints
- Output values only change on the rising edge of
CLK(0 to 1 transition). Q3_baris the logical NOT ofQ3at all times.- The next state of
Q0is determined by the value ofQ3_barimmediately before the clock edge.
Topics
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