  We investigate the quantum tunneling of electrons in an AA-stacked bilayer
graphene (BLG) $n$-$p$ junction and $n$-$p$-$n$ junction. We show that Klein
tunneling of an electron can occur in this system. The quasiparticles are not
only chiral but are additionally described by a `cone index'. Due to the
orthogonality of states with different cone indexes, electron transport across
a potential barrier must strictly conserve the cone index and this leads to the
protected cone transport which is unique in AA-stacked BLG. Together with the
negative refraction of electrons, electrons residing in different cones can be
spatially separated according to their cone index when transmitted across an
$n$-$p$ junction. This suggests the possibility of `cone-tronic' devices based
on AA-stacked BLG. Finally, we calculate the junction conductance of the
system.
