A micropower analog-to-digital converter and an algorithm for an interface system for an infrared imaging system

• Main Author: Huang, Li.
• Other Authors: Chang, Joseph Sylvester
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Electronic circuits
• Online Access: http://hdl.handle.net/10356/17912
• Institution: Nanyang Technological University

This project is part of an on-going research collaboration between MIT and NTU on the development of a novel imaging system – a Multispectral Infrared Detector Arrays (MIDAS) on Read-Out Integrated Circuit (ROIC). The project pertains to a design of a novel micropower monolithic 12-bit Successive Approximation Register (SAR) Analog-to-Digital Converter (ADC) for ROIC and a realization of novel image reading algorithms for the interface between the MIDAS-on- ROIC and a display. Of specific interest, a micropower ADC that is integrated onto ROIC is a dominant factor for the design a low-power and low-noise image system. Moreover, the vertically stacked image sensors in MIDAS (against the conventional planar image sensors) require a set of completely new interface algorithms. In the SAR-ADC design, a novel hybrid technique of voltage scaling and capacitive matching is proposed to improve the matching of on-chip resistors and capacitors, hence achieving the 12-bit resolution without expensive post-fabrication process. Further, a highly sensitive and high speed micropower comparator together with a simple and effective SAR logic circuit is also proposed. On the basis of computer simulations, the proposed SAR-ADC can achieve ultra low power consumption in operation (188uW with 3.3V voltage supply). Layout of the proposed SAR-ADC is partially realized. A novel interface algorithm for vertically-stacked image sensor is realized in MATLAB on the basis of the standard gamma correction, resulting in a linear conversion interface between the MIDAS-on-ROIC and the display. The proposed MATLAB algorithms are suitable for both still image display and video display.