A shift register with its Q’ of the last stage connected to input of first stage is calleda.Ripple Counterb.Ring Counterc.FSMd.Johnson Counter

To determine which option describes a shift register with its Q’ of the last stage connected to the input of the first stage, let's analyze each option:

1. Ripple Counter: This is a type of binary counter that is often not described by connecting the output of the last stage back to the first stage.

2. Ring Counter: A type of counter that circulates a single '1' bit around the register; typically, only the Q output is used to connect.

3. FSM (Finite State Machine): This is a computational model that can be in one of a finite number of states but does not directly relate to the question about a shift register.

4. Johnson Counter: This is a specific type of shift register where the inverted output of the last flip-flop (Q’) is fed back into the first stage, allowing it to effectively count in a different manner (up to 2n states where n is the number of flip-flops).

Conclusion

The correct answer is d. Johnson Counter. This type of counter fits the description provided, where the output Q' is connected back to the input of the first stage of the register.