ECE 375: Digital Design II

Class 17

Making 3 I/P LUT with 2, 2 I/P LUTs

Example 3:
F1 LUT
0
0
0
1
F2 LUT
0
1
1
1

Note: Using 2 LUTs as a 3 I/P LUT could be a good idea if the X3 signal is slower or more timing sensitive.

Example 4:

This is one way of creating the logic but requires a lot of resources

F = (X1 + X2)X3 + X1'X2'X3' F1 = X1 + X2 F2 = F1X3 + F1'X3' = F1 ⊙ X3

But how many LUTs are needed? 2, one for F1, one for F2

F1 LUT (X1,X2)
0
1
1
1
F2 LUT (F1,X3)
1
0
0
1