A ring counter or Johnson counter is a type of sequential circuit composed of a circular shift register with only one flip-flop set at a time. In a straight ring counter, the output of the last stage is fed back to the first stage input, circulating a single bit around the ring. In a Johnson counter, the complement of the output is fed back, doubling the number of states and dividing the input clock frequency by twice the number of stages rather than the number of stages like a straight ring counter. Ring counters can generate different timing signals like multiphase square waves.