Submicron CMOS circuit simulation model accurate from liquid nitrogen to room temperature

Abstract

A drain-current device model for circuits operating over the temperature range from liquid nitrogen to room temperature has been developed. The model is accurate for short (> 0.3 μm) surface channel CMOS devices and has been used to predict circuit performance and switching characteristics at varying temperatures. The model includes temperature dependance of important device parameters such as "apparent" mobility μ, saturation velocity and threshold voltage. Model parameters are designed for extraction at room temperature; except for device threshold which is measured at the operating temparature. This allows simple extraction of model parameters and results in an accurate description of device currents. The model is incorporated in the ASTAP circuit simulation program and is used to project improvement in delay of optimized low temperature CMOS over room temperature CMOS. The model is also used to design temperature insensitive off-chip driver/receiver circuits for maximum noise immunity between 77°K and 125°K using a 0.5μm liquid-nitrogen CMOS technology.