Date of Graduation

5-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Electrical Engineering

Advisor/Mentor

H. Alan Mantooth

Committee Member

Zhong Chen

Second Committee Member

Jia Di

Third Committee Member

Jeff Dix

Keywords

sustainability, fabrication run, circuits, signal conditioning module, module design

Abstract

The objective of the work described in this dissertation paper is to develop a prototype electronic module on a low-temperature co-fired ceramic (LTCC) material. The electronic module would perform signal conditioning of sensor signals (thermocouples) operating under extreme conditions for applications like gas turbines to collect data on the health of the turbine blades during operation so that the turbines do not require shutdown for inspection to determine if maintenance is required. The collected data can indicate when such shutdowns, which cost $1M per day, should be scheduled and maintenance actually performed. The circuits for the signal conditioning system within the prototype module must survive the extreme temperature, pressure, and centrifugal force, or G-force, present in these settings. Multiple fabrication runs on different integrated silicon carbide (SiC) process technologies have been carried out to meet the system requirements. The key circuits described in this dissertation are - two-stage op amp topologies and voltage reference, which are designed and fabricated in a new SiC CMOS process. The SiC two-stage op amp with PFET differential input pair showed 48.9 dB of DC gain at 500oC. The voltage reference is the first in SiC CMOS technology to employ an op amp-based topology. The op amp circuit in the voltage reference is a two-stage with NFET differential input pair that uses the indirect compensation technique for the first time in the SiC CMOS process to provide 42.5 dB gain at 350oC. The designed prototype module implemented with these circuits was verified to provide signal conditioning and signal transmission at 300oC. The signal transmission circuit on the module was also verified to operate with a resonant inductive wireless power transfer method at a frequency of 11.8 MHz for the first time. A second prototype module was also developed with the previously fabricated 1.2 µm SiC CMOS process. The second module was successfully tested (with wired power supply) to operate at 440oC inside a probe-station and also verified for the first time to sustain signal transmission (34.65 MHz) capability inside a spin-rig at a rotational speed of 10,920 rpm. All designed modules have dimensions of (length) 68.5 mm by (width) 34.3 mm to conform to the physical size requirements of the gas turbine blade.

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