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 Pb
_0,80
Sn
_0,20
Te photovoltaíc detector array at 77 K to a silicon CCD multiplexer specially designed for the readout of infrared detectors. At present the 2.10
¹⁰
W
^-1
cmHz
^1/2
measured equivalent detectivity is limited by the coupling noise in the channel of each input MOSFET. A 5.10
¹⁰
W
^-1
cmHz
^1/2
equivalent detectivity is expected with 8 - 12 μm detectors operated at 60 K.