Design and Evaluation of a Silicon-Germanium BiCMOS Operational Amplifier for Wide-Temperature Applications
Date Issued
August 2025
Author(s)
Seaver Alex Ray
University of Tennessee at Knoxville
Advisor(s)
Benjamin J. Blalock
Additional Advisor(s)
Nicole McFarlane
Gong Gu
Nicole McFarlane$$sl-0
Gong Gu$$sl-0
Abstract
The operational amplifier is a cornerstone component of analog electronics design, serving critical roles in innumerable applications such as sensing, signal conditioning and filtering, data acquisition, analog computation, communications, and control systems. Owing to their ubiquity, it is inevitable that engineers wish to use operational amplifiers in extreme environments such as in space exploration where temperatures can range from nearly absolute zero (i.e., 0K or about −273◦C [degrees Celsius]) to well over 125◦C. However, designing amplifiers to operate reliably over such wide temperature requires more care than is commonly given to the design of commercial off-the-shelf amplifiers, which are typically designed to operate over temperature ranges no wider than −55◦C to 125◦C. While CMOS based amplifiers can be designed to operate down to deep cryogenic temperatures, it is desirable to turn towards bandgap-engineered materials to overcome challenges specific to such wide temperature design, such as reduced precision, decreased long-term reliability, and degraded radiation tolerance at extreme temperatures. For space exploration applications, it is beneficial to develop a modular library of mixed-signal integrated circuits (ICs) known to be reliable in extreme environments in order to enable speedy design of integrated electronic systems for space missions. This work develops the design of an integrated two-stage operational amplifier for use in such a modular extreme-environment IC library. The amplifier is designed in a commercially available 90nm BiCMOS process featuring silicon-germanium heterojunction bipolar transistors (HBTs) and is evaluated across wide temperature from −180◦C to 125◦C, with in situ tests also demonstrating successful operation at 4.2K (−269◦C) as part of a linear voltage regulator (LVR).
Degree
Master of Science
Major
Electrical Engineering
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