  We report the phase coherent splitting of Bose-Einstein condensates by means
of a phase grating produced near the surface of a micro-electronic chip. A
lattice potential with a period of $4\mu$m is generated by the superposition of
static and oscillating magnetic fields. Precise control of the diffraction is
achieved by controlling the currents in the integrated conductors. The
interference of overlapping diffraction orders is observed after 8ms of
propagation in a harmonic trap and subsequent ballistic expansion of the atomic
ensemble. By analyzing the interference pattern we show a reproducible phase
relation between the diffraction orders with an uncertainty given by the
resolution of the diffraction grating.
