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Proceedings Paper

Photonic analog-to-digital conversion based on oversampling techniques
Author(s): Barry L. Shoop; Pankaj K. Das; Eugene K. Ressler Jr.; Timothy J. Talty
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Paper Abstract

A novel photonic approach to analog-to-digital (A/D) conversion based on temporal and spatial oversampling techniques in conjunction with a smart pixel hardware implementation of a neural algorithm is described. In this approach, the input signal is first sampled at a rate higher than that required by the Nyquist criterion and then presented spatially as the input to the 2D error diffusion neural network consisting of M X N pixels. The neural network processes the input oversampled analog image and produces an M X N pixel binary output image which is an optimum representation of the input analog signal. Upon convergence, the neural network minimizes an energy function representing the frequency-weighted squared error between the input analog image and the output halftoned image. Decimation and low-pass filtering techniques, common to oversampling A/D converters, digitally sum and average the M X N pixel output binary image using high-speed digital electronic circuitry. By employing a 2D smart pixel neural approach to oversampling A/D conversion, each pixel constitutes a simple oversampling modulator thereby producing a distributed A/D architecture. Spectral noise shaping across the array diffuses quantization error thereby improving the signal-to-noise ratio performance. Here, each quantizer within the network is embedded in a fully- connected, distributed mesh feedback loop which spectrally shapes the overall quantization noise significantly reducing the effects of component mismatch typically associated with parallel or channelized A/D approaches. The 2D neural array provides higher aggregate bit rates which can extend the useful bandwidth of oversampling converters.

Paper Details

Date Published: 18 July 2000
PDF: 14 pages
Proc. SPIE 4042, Enabling Photonic Technologies for Aerospace Applications II, (18 July 2000); doi: 10.1117/12.391914
Show Author Affiliations
Barry L. Shoop, U.S. Military Academy (United States)
Pankaj K. Das, U.S. Military Academy (United States)
Eugene K. Ressler Jr., U.S. Military Academy (United States)
Timothy J. Talty, U.S. Military Academy (United States)

Published in SPIE Proceedings Vol. 4042:
Enabling Photonic Technologies for Aerospace Applications II
Edward W. Taylor; Andrew R. Pirich, Editor(s)

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