  The tunneling conductance between a metal and a multiband s-wave
superconductor with a thin layer of single-band s-wave superconductor
sandwiched in between is examined in this paper. We show that an in-gap peak in
conductance curve is found as a result of the formation of in-gap bound state
between the single-band and multiband superconductor junctions if the phases of
the superconducting order parameters of the multiband superconductor are
frustrated. The implication of this result in determining the gap symmetry of
the iron-based superconductors is discussed.
