  We construct a class of renormalizable models for lepton mixing that generate
predictions given in terms of the charged-lepton mass ratios. We show that one
of those models leads, when one takes into account the known experimental
values, to almost maximal CP-breaking phases and to almost maximal neutrinoless
double-beta decay. We study in detail the scalar potential of the models,
especially the bounds imposed by unitarity on the values of the quartic
couplings.
