Mod 2 Ring Counter (with D flip-flop)

Ring counters are one of the most important applications of shift registers. They are created by connecting multiple flip-flops to one another (such that the output of one flip-flop is the input for another), and by connecting the output of the last flip-flop to the input of the first flip-flop.

For a mod 2 ring counter, two flip-flops will be required. Recall that the number of states that can be counted by a ring counter is equal to the number of flip-flops being used. Since a mod 2 ring counter can count up to 2 states, 2 flip-flops will be required.

Since a ring counter is a synchronous counter, the clock needs to be in “ON” state so that state transitions can happen and the ring counter can function normally.

Circuit Diagram :

From the diagram, we can see that D1 = Q0 and D0 = Q1

Table :
Combining the excitation table and the state table here for convenience.

State Diagram :

Attention reader! Don’t stop learning now. Get hold of all the important CS Theory concepts for SDE interviews with the CS Theory Course at a student-friendly price and become industry ready.

My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using or mail your article to See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.

Article Tags :

Be the First to upvote.

Please write to us at to report any issue with the above content.