Signal Processing of Infrared Detectors with CCD´s

Because of its low-noise capability, high dynamic range and low power consumption, the CCD appears to be a potentially very useful tool for signal processing of linear and two-dimensional focal-plane arrays of infrared detectors. The signal processing operations include time delay and integration (TDI), multiplexing and filtering. We discuss in this paper the critical parameters of the detector-to-CCD coupling and the related limitations for the various kinds of thermal imaging scanners. Some of these parameters have been measured at 300 K and 77 K, especially the CCD´s input transconductance, the input MOSFET coupling noise, the transfer noise in the CCD channel, and the threshold voltage dispersion. We also give some experimental results on the direct-injection coupling of a Pb0,80 Sn0,20 Te photovoltaíc detector array at 77 K to a silicon CCD multiplexer specially designed for the readout of infrared detectors. At present the 2.10¹⁰ W^-1 cmHz^1/2 measured equivalent detectivity is limited by the coupling noise in the channel of each input MOSFET. A 5.10¹⁰ W^-1 cmHz^1/2 equivalent detectivity is expected with 8 - 12 ¿m detectors operated at 60 K.