Date of Award
Doctor of Philosophy in Electrical Engineering - (Ph.D.)
Electrical and Computer Engineering
N. M. Ravindra
This thesis research was aimed at investigating and designing novel architectures required for ultra high frame rate (UHFR) imagers capable of operating at frame rates in excess of 106 frames/sec. To demonstrate the feasibility of these architectures, a 180 x 180 element UHFR-I imager was designed and fabricated. The imager chip stored the latest 32 frames at its on-chip memory locations rather than performing a continuous readout. It was demonstrated that this architecture approach could achieve a frame acquisition rate of 2 x 106 frames/sec. Additionally, other novel design features were incorporated to minimize optical cross talk and output amplifier noise, and maximize charge handling capacity.
Two-dimensional (2-D) process and device simulations were performed to optimize optical cross talk and results compared favorably with experimental data of the fabricated chip. This tested imager was fabricated at the research laboratory of Sarnoff Corporation and had 4-levels of polysilicon, 3-levels of metal, eight implants and 21 photo mask levels. Simulations were also performed to characterize optical cross talk as a function of wavelength, optical shield aperture and epi-substrate doping. The measured value of optical cross talk was at least a factor of 40 times lower and maximum frame rate was a factor of 4 higher than previously published results for very high frame rate (VHFR) imager.
The experimental results were used to design a new 64 x 64 element UHFR-II imager with an architecture capable of an image capture rate of 107 frames/sec. This architecture requires only 3-levels of polysilicon and 2-levels of metal and stores the latest 12 frames at its on-chip memory locations. Simulation results indicate that a frame rate of 107 frames/sec can certainly be obtained.
Kabra, Rakesh K., "Design and characterization of ultra high frame rate burst image sensors" (1997). Dissertations. 948.