USING KMAPS TO DESIGN COUNTER
Q Design MOD3 ripple counter using (a) Observing outputs (b) Kmaps to design the circuit.
Ans: (a)We can design the MOD 3 counter using 2 FFs as 3 is less than 4 i.e. 2^{2} and greater than 2. We can see directly that as we have to reset the counter only after 2 i.e. when output is 3 we reset the counter and hence we need to reset only when we have Q0= 1 & Q1=1. Now firstly design MOD4 counter using 2 FFs and then take NAND of Q0 & Q1 and feed the output to CLEAR of both FFs.
(b) We firstly draw state diagram of the counter required as:
And we have the general circuit to design the other than MOD 2^{ n} then we have the general circuit as
And now we draw a table to list the different input combinations to Combinational circuit and their corresponding output as:
Q1 Q0 OUTPUT of reset logic
0 0 1
0 1 1
1 0 1
1 1 0
And using Kmap as
And hence we get the whole circuit for MOD3 counter as
