SiGe BiCMOS comparator for extreme environment applications

This paper presents a 90 nm SiGe BiCMOS comparator designed for extreme environment use. A unique circuit characteristic of this comparator topology is that it uses only one NMOS transistor in the circuit. The rest of the circuit is comprised of PMOS transistors and NPN HBTs in order to maintain radiation hardiness. The circuit was simulated across a temperature range of -195 °C to 155 °C. The circuit was simulated at cryogenic temperatures using several models developed at the University of Arkansas (UA) and at Georgia Tech. The comparator produces a maximum resolution of 500 μV with an input range of 0.05-0.6 V in a 1.2 V process. A maximum propagation delay of less than 20 ns was also achieved. These specifications were based off of its intended application in a successive approximation register analog-to-digital converter also being developed at the UA as part of a NASA Space Technology Research Opportunities-Early Stage Innovations (STRO-ESI) project.