Following is a refresher on the XNOR gates.
Figure 1 XNOR gate
Alternate equation for an XNOR gate is :
O = (A)bar * (B)bar + A * B
This can be derived using Kmaps as following.
Figure 2. Kmap for XNOR gate.
We know that the equation for a 2:1 MUX is of following form :
Out = S * A + (S)bar * B.
We need to turn this of the form
O = (A)bar * (B)bar + A * B
It seems easy enough to achieve this. In the 2:1 MUX equation, if we tie (A)bar in place of B, we get
Out = S * A + (S)bar * (A)bar
This is the equation of XNOR gate for inputs S and A.
Figure 3 XNOR using 2:1 MUX
Do you think we are done with 2:1 MUX series now ? There is still some more devices that we can make. Will continue in next post.
-SS