(A) Shutter-less micro-bolometer thermal imaging system using multiple digital correlated double sampling

Abstract

This dissertation proposes a multiple digital correlated double sampling (MDCDS) readout method for uncooled microbolometer infrared focal plane array (IRFPA) thermal imaging sensor. The proposed MDCDS readout method employing a newly designed reference-cell has the output characteristics with a strong tolerance to process-, voltage- and temperature- (PVT) variation by forming a differential current bridge in discrete time domain. Therefore, MDCDS readout method greatly reduces PVT variation induced fixed pattern noise (FPN) and also alleviates the burden of requirements for the both hardware and software in IRFPA thermal imaging system. As a result, it features much relaxed non-uniformity correction (NUC) process, easier TEC-less operation and Shutter-less operation. The readout integrated circuit (ROIC) and microbolometer infrared detector was fabricated in 0.35 μm CMOS and amorphous silicon MEMS process respectively. The fabricated thermal imaging sensor has NETD performance of 0.1 kelvin even though the mechanical shutter is not used.