Emad Andarawis

Silicon Carbide High Temperature Operational Amplifier

Development of silicon carbide operational amplifier offers an attractive alternative building block for the replacement of silicon and silicon-on-insulator analog circuits in harsh environment applications. NMOS-based enhancement mode silicon carbide device technology was utilized to demonstrate feasibility of operational amplifiers for use in harsh environment applications. This study reports on the results of characterization of operational amplifiers at room temperature and high temperatures up to 350°C. The development of high temperature packaging techniques enabled assembly of a functional oscillator board tested up to 350°C. A test fixture with high temperature sockets enabling quick swap of operational amplifiers is also discussed as an important tool in high temperature electronics research and development.

300°C Silicon Carbide Integrated Circuits

MOSFET-based integrated circuits were fabricated on silicon carbide (SiC) substrates. SiC devices can operate at much higher temperatures than current semiconductor devices. Simple circuit components including operational amplifiers and common source amplifiers were fabricated and tested at room temperature and at 300°C. The common source amplifier displayed gain of 7.6 at room temperature and 6.8 at 300°C. The operational amplifier was tested for small signal open loop gain at 1kHz, measuring 60 dB at room temperature and 57 dB at 300°C. Stability testing was also performed at 300°C, showing very little drift at over 100 hours for the individual MOSFETs and the common source amplifier.

Harsh-Environment Solid-State Gamma Detector for Down-hole Gas and Oil Exploration

The goal of this program was to develop a revolutionary solid-state gamma-ray detector suitable for use in down-hole gas and oil exploration. This advanced detector would employ wide-bandgap semiconductor technology to extend the gamma sensors temperature capability up to 200 C as well as extended reliability, which significantly exceeds current designs based on photomultiplier tubes. In Phase II, project tasks were focused on optimization of the final APD design, growing and characterizing the full scintillator crystals of the selected composition, arranging the APD device packaging, developing the needed optical coupling between scintillator and APD, and characterizing the combined elements as a full detector system preparing for commercialization. What follows is a summary report from the second 18-month phase of this program.

Reliability of Silicon Carbide Integrated Circuits at 300°C

Silicon carbide based integrated circuits (ICs) have the potential to operate at temperatures exceeding that of conventional semiconductors such as silicon and silicon on insulator. Analog and digital silicon carbide (SiC) based circuits were fabricated and characterized at room temperature and 300°C. An operational amplifier and a ring oscillator were tested for prolonged period of time to evaluate their stability and reliability at 300°C. More than 1,000 hours was achieved with the operational amplifier without failures and the ring oscillator operated for almost 300 hours.

A signal conditioning unit for high temperature applications

This paper covers the design and testing of a high temperature signal conditioning unit for integration with temperature and strain gauge sensors. The developed signal conditioning unit system includes an instrumentation amplifier, a single-ended to differential converter, an Analogue to Digital converter, and an ARINC 429 transmitter. This unit was designed and fabricated on 1 μm Silicon-on-Insulator CMOS (Complementary Metal Oxide Semiconductor) technology and has been characterized up to 225 degrees Celsius.

Radio-frequency plasma transducer for use in harsh environments

We describe a compact transducer used to generate and modulate low-intensity radio-frequency atmospheric pressure plasma (RF-APP) for high temperature gap measurement and generation of air-coupled ultrasound. The new transducer consists of a quarter-wave transmission line where the ground return path is a coaxial solenoid winding. The RF-APP is initiated at the open end of the transmission line and stabilized by passive negative feedback between the electrical impedance of the plasma and the energy stored in the solenoid. The electrical impedance of the plasma was measured at the lower-voltage source end of the transducer, eliminating the need to measure kilovolt-level voltages near the discharge. We describe the use of a 7 MHz RF-APP prototype as a harsh-environment clearance sensor to demonstrate the suitability of plasma discharges for a common nondestructive inspection application. Clearance measurements of 0-5 mm were performed on a rotating calibration target with a measurement precision of 0.1 mm and a 20 kHz sampling rate.

Design methodology for powerline coupling circuit: a system-level and Monte Carlo simulation based approach

Robust design of powerline carrier communication (PLCC) system is essential due to great advances in utilization of PLCC technology across diverse applications. Powerline communication system design is complicated by noise conducted by the media and variable channel loss and signal propagation. The coupling circuit is a critical element of a PLCC system. Traditional methods for robust design, such as Monte Carlo, may require performing prohibitive number simulations. This paper proposes a computationally efficient, system-level response surface modeling (SRSM) method for the robust design of coupling circuit and PLCC system. The SRSM method is fully automated and its performance can be directly compared with the Monte Carlo simulation method. The results obtained agree closely with those of traditional Monte Carlo method, while significantly reducing the required number of simulations.