  Under dim lighting conditions, the output of Dynamic Vision Sensor (DVS)
event cameras is strongly affected by noise. Photon and electron shot-noise
cause a high rate of non-informative events that reduce Signal to Noise ratio.
DVS noise performance depends not only on the scene illumination, but also on
the user-controllable biasing of the camera. In this paper, we explore the
physical limits of DVS noise, showing that the DVS photoreceptor is limited to
a theoretical minimum of 2x photon shot noise, and we discuss how biasing the
DVS with high photoreceptor bias and adequate source-follower bias approaches
optimal noise performance. We support our conclusions with pixel-level
measurements of a DAVIS346 and analysis of a theoretical pixel model.
