Research Interests Vision Sensors: We are studying novel current-mode image sensors with analog spatial processing and a new pixel array design, in which several techniques are combined to improve the quality of the images. Included in the design is a new addressing scheme that allows a group of pixels to share the same readout circuitry, therefore reducing the pixel size and increasing the resolution. The new design has removed the in-pixel accessing switches, and uses velocity saturated operation in order to increase the readout linearity. We are also integrating a successive approximation ADC on the imager. The ADC is natively current mode, and is designed to interface directly with the current mode pixels without the need for sample-and-hold circuits or current-to-voltage converters. Sensor for Polarization Imaging: We are also developing a focal plane imaging sensor capable of real time extraction of polarization information. The imaging system consists of a photo array of linear current mode active pixel sensors and analog processing circuitry for computation of the Stokes parameters. A dual-tier thin film micro-polarizer array has been deposited on the imager. A commercially available thin film polarizer is used to create an array of micro-polarizers. The thin film polarizer consists of an iodine-doped Polyvinyl Alcohol (PVA) layer which is patterned and etched using RIE. The measured extinction ratios of the filters are 1000 and 100 for the blue/green and red spectrum, respectively. Mixed mode Integrated Circuits for Data Acquisition Systems and Communications: We are currently exploring different architectures and algorithms to realize high performance analog-to-digital converters. One project deals background calibration schemes to correct for any residual non-idealities (linear and non-linear) in pipe-lined analog-to-digital converters. We are also developing CMOS circuits for RF communications using AlN Contour-Mode Piezoelectric Resonators in collaboration with Prof. G. Lucca’s group.
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Linear Current-Mode Active Pixel Sensor (with Ralf M. Philipp, David Orr, Viktor Gruev, and Ralph Etienne-Cummings), Departmental Papers (ESE) (2007)
A current mode CMOS active pixel sensor (APS) providing linear light-to-current conversion with inherently low...
A Spectral Conversion Approach to Single-Channel Speech Enhancement (with Athanasios Mouchtaris, Paul Mueller, and Panagiotis Tsakalides), Departmental Papers (ESE) (2007)
In this paper, a novel method for single-channel speech enhancement is proposed, which is based...
Cort-X II: Low Power Element Design of a Large-Scale Spatio-Temporaral Pattern Clustering System (with Jie Yuan, Ning Song, and Nabil H. Farhat), Departmental Papers (ESE) (2007)
Complex spatio-temporal patterns can be clustered using a network of parametrically coupled logistic maps. This...
Low Fixed Pattern Noise Current-mode Imager Using Velocity Saturated Readout Transistors (with Zheng Yang and Viktor Gruev), Departmental Papers (ESE) (2007)
This paper described a novel current-mode active pixel sensor (APS) imager. Conversion of photodiode voltage...
Two Transistor Current Mode Active Pixel Sensor (with Viktor Gruev, Zheng Yang, and Ralph Etienne-Cummings), Departmental Papers (ESE) (2007)
A novel current mode active pixel sensor for high resolution imaging is presented. The photo...