Logic Diagram Of Johnson Counter. The counter has an asynchronous reset or clear input which brings the outputs to 0 as soon as the reset signal is asserted. The only change is that the output of the last flip flop is connected to the input of the first flip flop in case of ring counter but in case of shift resister it is taken as output.
Total number of unused states 2 n 2n. Hence initially the ops are q 3 q 2 q 1 q 0 0000. The johnson counter has same number of flip flop but it can count twice the number of states the ring counter can count.
Total number of used states 2n.
It is also called as twisting ring counter or switch tail counter. Below is the diagram of the 4 bit johnson counter. Modified 49 years ago by juilee 82k. The schematic of 4 bit johnson counter consists of 4 d flip flops or 4 jk flip flops.