A High Temperature Reference Voltage Generator with SiC Transistors

Natural resources are always collected from harsh environments, such as mines and deep wells. Currently, depleted oil wells force the gas and oil industry to drill deeper. As the industry drills deeper, temperatures of these wells can exceed 210 °C. Contemporary downhole systems have reached their depth and temperature limitations in deep basins and are no longer meet the high requirements in harsh environment industries. Therefore, robust electronic systems that can operate reliably in harsh environments are in high demand. This thesis presents a high temperature reference voltage generator that can operate reliably up to 250 °C for a downhole communication system. The proposed reference voltage generator is designed and prototyped using 4H-SiC bipolar transistors. Silicon carbide (SiC) is a semiconductor material that exhibits wide bandgap, high dielectric breakdown field strength, and high thermal conductivity. Due to these properties, it is suitable for high-frequency, high-power, and high-temperature applications. For bypassing the lack of high temperature p-type SiC transistors (pnp BJT, PMOS) and OpAmp inconvenience, an all npn voltage reference architecture has been developed based on Widlar bandgap reference concept. The proposed reference voltage generator demonstrates for the first time a functional high temperature discrete reference voltage generator that uses only five 4H-SiC transistors to achieve both temperature and supply independent. Measurement results show that the proposed voltage reference generator provides an almost constant negative reference voltage around -3.23 V from 25 °C to 250 °C regardless of any change in power supply with a low temperature coefficient (TC) of 42 ppm/°C.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Electrical Engineering

Department dc:contributor.department

Electrical and Computer Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2016

Author dc:creator

• Zhang, ZiHao

Chair dc:contributor.committeechair

• Ha, Dong Sam

Committee members dc:contributor.committeemember

• Li, Qiang
• Koh, Kwang-Jin

• High temperature
• Extreme Environment
• Silicon Carbide
• Reference Voltage Generator
• Downhole Communication System

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

vt_gsexam:8798

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/72888