  In this paper, some preliminary considerations on the feedback systems for
FCC-ee are developed. Bunch-by-bunch feedback systems have been designed in the
last years for other e+/e- colliders like PEP-II, KEKB, DAFNE, SuperB and
SuperKEKB. In all these cases, similar approaches have been implemented, even
if some design variations have been suitable or necessary for different
reasons. Bunch-by-bunch feedback systems are based on the concept that the
barycenter of each bunch moves with harmonic motion around the equilibrium
point in three planes (L, H, V). The feedback copes with the forcing excitation
by producing damping correction for each individual bunch. This is possible
managing every single bunch by a dedicated processing channel in real time. For
FCC-ee the very high number of stored bunches requires much more power in terms
of processing capability for the feedback systems. Ring length (100 Km) and
very low fractional tunes must be also considered requiring for a more
effective strategy in the feedback system design.
