Two bit ripple counter used two flip-flops. There are four possible states from 2 – bit up-counting I.e. 00, 01, 10 and 11.
- The counter is initially assumed to be at a state 00 where the outputs of the tow flip-flops are noted as Q1Q0. Where Q1 forms the MSB and Q0 forms the LSB.
- For the negative edge of the first clock pulse, output of the first flip-flop FF1 toggles its state. Thus Q1 remains at 0 and Q0 toggles to 1 and the counter state are now read as 01.