In this letter it is proven that any piecewise-linear (PWL) function can be
realized as the sum of a definite number of basic PWL functions, like that
implemented in the classical Cellular Neural Network (CNN) structure by L.
Chua. This allows us to consider the basic Chua's PWL function as a fundam
ental unit to build up a generic PWL function and, thus, to extend the clas
s of nonlinear dynamics that can be realized by CNNs to a more wide class i
ncluding PWL approximation of any nonlinearity. Moreover, an example of the
cell realization of such a CNN is reported.