  We discuss the general formalism for the calculation in light-cone quark
models of the fully unintegrated, off-diagonal quark-quark correlator of the
nucleon. The corresponding distributions in impact parameter space are the
Wigner or phase-space distributions. The results obtained in two different
light-cone quark models in the case of unpolarized quarks in an unpolarized
proton are very similar and present a non-trivial shape which can be understood
as due to the orbital motion of the quarks.
