Logic Optimization - Two-level Versus Multi-level Representations

Two-level Versus Multi-level Representations

If we have two functions F₁ and F₂:

The above 2-level representation takes six product terms and 24 transistors in CMOS Rep.

A functionally equivalent representation in multilevel can be:

P = B + C.

F₁ = AP + AD.

F₂ = A'P + A'E.

While the number of levels here is 3, the total number of product terms and literals reduce because of the sharing of the term B + C.

Similarly, we distinguish between sequential and combinational circuits, whose behavior can be described in terms of finite-state machine state tables/diagrams or by Boolean functions and relations respectively.