Design and simulation of mixed analog-digital circuits working at low temperature, typically between 77 K and 200 K, requires advanced compact models incorporating most of the physical effects occurring in cooled MOSFET. In this paper, some specific effects, such as freeze-out in LDD regions or quantization of the inversion layer in silicon sub-bands, observed at intermediate temperature are described and tentatively modeled. This study is performed on a dual gate oxide CMOS technology with 0.18 mu m/1.8 V and 0.35 mu m/3.3 V MOSFET transistors. Some improvements of compact models will allow a very precise description of MOS transistors for design of ultra-high performance infrared CMOS imagers working at cryogenic temperatures. Data on low frequency noise and transistor matching at low temperature are also presented. (C) 2011 Elsevier Ltd. All rights reserved.