Noise Performance of Time-Domain CMOS Image Sensors

Abstract

Temporal noise is the main disadvantage of CMOS image sensors when compared to charg‐ ed couple devices (CCDs) sensor. The typical 3T active pixel sensor (APS) architecture presents as main noise sources the photodiode shot noise, the reset transistor and follower thermal and shot noise, the amplifier thermal and 1/f noise, the column amplifier thermal and reset noise (Zheng, 2011; Brouk, 2010; Jung, 2005; Tian, 2001; Derli, 2000; Yadid-Pecht, 1997). In order to reduce the APS noise several approaches have been proposed in the litera‐ ture. Some of these approaches are the use of high gain preamplifiers, correlated multiple sampling (CMS) and low bandwidth column-parallel single slope A/D converters (Sakaki‐ bara, 2005; Kawai, 2004; Suh, 2010; Lim, 2010; Yoshihara, 2006; Chen, 2012). However, APS in time domain has as advantage to show lower source of noise since it is composed only by a photodiode, a reset transistor and a voltage comparator. It shows as noise source only the reset transistor and the photodiode. Therefore, in principle, APS in time domain may presents lower overall noise.