  We perform a comparative study of the phase noise induced in the lasers used
for Bragg diffraction in a Bose-Einstein condensate-based quantum gravimeter
where the Bragg beams are generated using two different configurations. In one
of the configurations, the Bragg beams that form the moving optical lattice are
generated using two different acousto-optic modulators. In the second
configuration, the Bragg beams are generated using a single acousto-optic
modulator carrying two phase-locked frequencies. The second configuration shows
a suppression of phase noise by a factor of 4.7 times in the frequency band
upto 10 $kHz$, the primary source of noise, which is the background acoustic
noise picked up by optical components and the optical table. We report a
sensitivity of 99.7 $\mu Gal/\sqrt Hz$ for an interferometric time of 10 $ms$.
