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Teledyne Digital Imaging has a long history of providing state-of-the-art sensors for both ground and space astronomy applications spanning visible to mid-infrared wavelengths. This paper provides an overview on recent technical developments of the COSMOS large format 8k x 8k deeply cooled CMOS camera for ground-based astronomy. Salient features of the custom back illuminated sensor developed for this camera are presented, including having a 10μm pixel pitch with dual conversion gain HDR (>100dB), very low temporal noise (< 1 e- rms) and dark current (<0.05 e-/p/s at - 25°C), greater than 90% quantum efficiency, as well as excellent linearity and response uniformity required for astronomy applications. The readout channel in the 64Mpixel sensor utilized in COSMOS consists of column-parallel two-stage oversampled analog-to-digital converters with programmable resolution from 14-to-16 bit output with 5 us row conversion time in 14- bit. While internal on-chip CDS is utilized to achieve nominal temporal noise values of 1.8erms with rolling shutter, external CDS with multi-sampling (CMS) further reduces temporal noise to sub-electron levels and when combined with dual conversion gain HDR readout, dynamic range of over 100dB is realized in a single exposure. The sensor and accompanied ceramic package having a 24 cm diagonal dimension are situated inside a permanently sealed light-weighted high-vacuum chamber thermally connected in parallel to 4 multi-stage TE coolers which are capable of cooling the sensor to < -40 °C in low power mode. |
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