What is the timing sequences for this circuit All outputs Q0

What is the timing sequences for this circuit? All outputs (Q0, Q1, Q2, and Q3) are initialized to \"0\". What do we call this circuit?

Solution

Clk 0 1 2 3 4 5 6 7 8

Q0 0 1 1 1 1 0 0 0 0

Q1 0 0 1 1 1 1 0 0 0

Q2 0 0 0 1 1 1 1 0 0

Q3 0 0 0 0 1 1 1 1 0

This is circuir is called twisted ring counterr or  Johnson counter ,which connects the complement of the output of the last shift register to the input of the first register and circulates a stream of ones followed by zeros around the ring

The Johnson counter generates a Gray code, a code in which adjacent states differ by only one bit.