  Graphene-based superlattice (SL) formed by a periodic gap modulation is
studied theoretically using a Dirac-type Hamiltonian. Analyzing the dispersion
relation we have found that new Dirac points arise in the electronic spectrum
under certain conditions. As a result, the gap between conduction and valence
minibands disappears. The expressions for the position of these Dirac points in
${\bf k}$-space and threshold value of the potential for their emergence were
obtained. At some parameters of the system, we have revealed interface states
which form the top of the valence miniband.
