Logic circuit Representation
Difference
Section titled “Difference”| Combinational | Sequential |
|---|---|
| No memory | Memory |
| No feedback loops | Feedback loops |
| Output depend only on the current input | Output depend on the input and current state |
Representation
Section titled “Representation”Truth Table :
- Unique signature of a boolean function
- Expensive representation Boolean Function :
- Can have many alternative boolean expressions
- Different boolean expressions lead to different gate realizations Canonical Form : Provide a unique algebraic signature
- Sum of miterms
- Product of maxterms
Canonical forms
Section titled “Canonical forms”Sum of Products (SOP)
Section titled “Sum of Products (SOP)”- Minterm : Product of literals (AND)
- Each row has a minterm
- Each minterm is true for that row and only that row
- Find all input combinations for which the output of the function is True
We can also write the sum of products as
Product of Sums (POS)
Section titled “Product of Sums (POS)”- Maxterm : Sum of literals
- Each row has maxterm
- Each maxterm is false for that row and only that row
- Find all input combinations for which the output of the function is False
We can also write the product of sums as