  In this note we present a general approach to construct large digraphs from
small ones. These are called expanded digraphs, and, as particular cases, we
show the close relationship between lifted digraphs of voltage digraphs and
line digraphs, which are two known ways to obtain dense digraphs. In the same
context, we show the equivalence between the vertex-splitting and partial line
digraph techniques. Then, we give a sufficient condition for a lifted digraph
of a base line digraph to be again a line digraph. Some of the results are
illustrated with two well-known families of digraphs. Namely, the De Bruijn and
Kautz digraphs, where it is shown that both families can be seen as lifts of
smaller De Bruijn digraphs with appropriate voltage assignments.
