  We solve the 2D Dirac equation describing graphene in the presence of a
linear vector potential. The discretization of the transverse momentum due to
the infinite mass boundary condition reduced our 2D Dirac equation to an
effective massive 1D Dirac equation with an effective mass equal to the
quantized transverse momentum. We use both a numerical Poincare Map approach,
based on space discretization of the original Dirac equation, and direct
analytical method. These two approaches have been used to study tunneling
phenomena through a biased graphene strip. The numerical results generated by
the Poincare Map are in complete agreement with the analytical results.
