Area

The area occupation of a circuit can be expressed in a closed form:

$$A=\sum_j \alpha_j W_j + \beta.$$ (6.30)

The area occupation is composed by two terms: a term directly proportional to the MOSFET widths (i.e. to the are occupied by the single MOSFET) and a term independent from the MOSFET widths (comprising, for example, the interconnect area). Both terms are, of course, positive, so the curve of the area occupied versus the MOSFET widths is a monotonic increasing curve²², that is a convex function.
Taking into account the interconnections area does not modify the property of the ``area'' function, since the only modification of equation (5.3) (page ) is in the term $\beta$ independent from the MOS widths²³.