CMOS long linear array for space application

Abstract

In the past years, it was expected that high-quality scientific imaging would remain out of reach for CMOS sensors since they lacked the required performance in noise, non-uniformity and dark signal levels and hence could not compete with high performances CCDs offering high quantum efficiency, large dynamic range and special modes as Time Delay Integration (TDI) and binning. However, CMOS imaging performs better than expected and allows today to address applications requiring: TDI capability coupled to image acquisition in pushbroom mode in order to enhance radiometric performances, Very long linear arrays thanks to stitching techniques, A high level of on-chip integration with both panchromatic TDI and multispectral linear sensors, On-chip correlated double sampling for low noise operation. This paper presents the design of a CMOS linear array, resulting from collaboration between Alcatel Alenia Space and Cypress Semiconductor, which take advantage of each of these emerging potentialities for CMOS technologies. It has 8000 panchromatic pixels with up to 25 rows used in TDI mode, and 4 lines of 2000 pixels for multispectral imaging. Main system requirements and detector trade-offs are presented, and test results obtained with a first generation prototype are summarized and compared with predicted performances.