3 May 2010 A 25μm pitch LWIR focal plane array with pixel-level 15-bit ADC providing high well capacity and targeting 2mK NETD
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CEA Leti has recently developed a new readout IC (ROIC) with pixel-level ADC for cooled infrared focal plane arrays (FPAs). It operates at 50Hz frame rate in a snapshot Integrate-While-Read (IWR) mode. It targets applications that provide a large amount of integrated charge thanks to a long integration time. The pixel-level analog-to-digital conversion is based on charge packets counting. This technique offers a large well capacity that paves the way for a breakthrough in NETD performances. The 15 bits ADC resolution preserves the excellent detector SNR at full well (3Ge-). These characteristics are essential for LWIR FPAs as broad intra-scene dynamic range imaging requires high sensitivity. The ROIC, featuring a 320x256 array with 25μm pixel pitch, has been designed in a standard 0.18μm CMOS technology. The main design challenges for this digital pixel array (SNR, power consumption and layout density) are discussed. The IC has been hybridized to a LWIR detector fabricated using our in-house HgCdTe process. The first electro-optical test results of the detector dewar assembly are presented. They validate both the pixel-level ADC concept and its circuit implementation. Finally, the benefit of this LWIR FPA in terms of NETD performance is demonstrated.
© (2010) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Fabrice Guellec, Fabrice Guellec, Arnaud Peizerat, Arnaud Peizerat, Michael Tchagaspanian, Michael Tchagaspanian, Eric De Borniol, Eric De Borniol, Sylvette Bisotto, Sylvette Bisotto, Laurent Mollard, Laurent Mollard, Pierre Castelein, Pierre Castelein, Jean-Paul Zanatta, Jean-Paul Zanatta, Patrick Maillart, Patrick Maillart, Michel Zecri, Michel Zecri, Jean-Christophe Peyrard, Jean-Christophe Peyrard, } "A 25μm pitch LWIR focal plane array with pixel-level 15-bit ADC providing high well capacity and targeting 2mK NETD", Proc. SPIE 7660, Infrared Technology and Applications XXXVI, 76603T (3 May 2010); doi: 10.1117/12.849684; https://doi.org/10.1117/12.849684

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