  We study chiral symmetry breaking in $\rm QED_3$ with $N_f$ flavors of
four-component fermions. A closed system of Schwinger-Dyson equations for
fermion and photon propagators and the full fermion-photon vertex is proposed,
which is consistent with the Ward-Takahashi identity. A simplified version of
that set of equations is reduced (in nonlocal gauge) to the equation for a
dynamical fermion mass function, where the one-loop vacuum polarization with
dynamically massive fermions has been taken into account. The linearized
equation for the fermion mass function is analyzed in real space. The
analytical solution is compared with the results of numerical calculations of
the nonlinear integral equation in momentum space.
