Abstract
Diffuse Optical Tomography (DOT) is a growing and viable imaging and diagnostic solution for applications in the biomedical research community. Recent advances have made integration of state-of-the-art optoelectronics and standard CMOS electronics possible and economically feasible. The detector is essentially a differential amplifier that compares the dark current of the photodiode and the current of the photodiode when detecting diffuse light, which must be synchronized with the optoelectronic sources.
This thesis investigates the necessary timing electronics for synchronization. Two different designs were presented. The first generated the pulse train as specified by the design at a static frequency. The design was proven to operate at the specified frequency through simulation and prototype development. Also, the response due to different frequencies other than the specified operating frequency was presented and discussed.
The second generated the pulse train through frequency multiplication thus removing the static frequency requirement. The multiplier was designed around a Phase-Locked Loop architecture and full analysis of the loop and loop components were presented along with functional specifications of the design. Also, a novel design for a divide-by-3 counter with a 50% duty cycle using standard binary counters is presented. Frequency range and pulse width specifications at different frequencies was also presented.
Thesis Committee: Prof. Sheila Prasad (Advisor), Prof. Dana Brooks, Prof. Clifton Fonstad (MIT)