Design, layout and simulation of 3T-APS pixels using the Open Sky130 Process Design Kit

The Active Pixel Sensor (APS) is the core of modern CMOS imagers, which are currently present in almost all image acquisition applications. The key structure of an APS pixel is constructed using a photosensitive block and three readout transistors, known as the 3T pixel. Based on a previous work, this paper describes the design, layout and extracted circuit simulation of four different readout circuits, using different MOSFET devices available from the open Sky130 Process Design Kit (PDK). The conversion gain and transient responses from each of the four pixels are compared, w.r.t. the output voltage swing, showing that open-source tools and this open PDK can be successfully employed on optimizing the design of this key sensor technology.