A Low Cost, High Dynamic Range, Versatile Digital Readout Integrated Circuit Unit Cell Prototype for Infrared Imaging Applications

abstract: Readout Integrated Circuits(ROICs) are important components of infrared(IR) imag ing systems. Performance of ROICs affect the quality of images obtained from IR imaging systems. Contemporary infrared imaging applications demand ROICs that can support large dynamic range, high frame rate, high output data rate, at low cost, size and power. Some of these applications are military surveillance, remote sensing in space and earth science missions and medical diagnosis. This work focuses on developing a ROIC unit cell prototype for National Aeronautics and Space Ad ministration(NASA), Jet Propulsion Laboratory’s(JPL’s) space applications. These space applications also demand high sensitivity, longer integration times(large well capacity), wide operating temperature range, wide input current range and immunity to radiation events such as Single Event Latchup(SEL). This work proposes a digital ROIC(DROIC) unit cell prototype of 30ux30u size, to be used mainly with NASA JPL’s High Operating Temperature Barrier Infrared Detectors(HOT BIRDs). Current state of the art DROICs achieve a dynamic range of 16 bits using advanced 65-90nm CMOS processes which adds a lot of cost overhead. The DROIC pixel proposed in this work uses a low cost 180nm CMOS process and supports a dynamic range of 20 bits operating at a low frame rate of 100 frames per second(fps), and a dynamic range of 12 bits operating at a high frame rate of 5kfps. The total electron well capacity of this DROIC pixel is 1.27 billion electrons, enabling integration times as long as 10ms, to achieve better dynamic range. The DROIC unit cell uses an in-pixel 12-bit coarse ADC and an external 8-bit DAC based fine ADC. The proposed DROIC uses layout techniques that make it immune to radiation up to 300krad(Si) of total ionizing dose(TID) and single event latch-up(SEL). It also has a wide input current range from 10pA to 1uA and supports detectors operating from Short-wave infrared (SWIR) to longwave infrared (LWIR) regions.Dissertation/ThesisMasters Thesis Electrical Engineering 201