Richard A Fields

US Patent:

62921193, Sep 18, 2001

Filed:

Jun 30, 1999

Appl. No.:

9/345295

Inventors:

Juan C. Carillo - Torrance CA
Bruce A. Ferguson - Redondo Beach CA
Richard A. Fields - Redondo Beach CA
Mark Kintis - Manhattan Beach CA
Elizabeth T. Kunkee - Manhattan Beach CA
Lawrence J. Lembo - Torrance CA
Stephen R. Perkins - Redondo Beach CA
David L. Rollins - Hawthorne CA
Eric L. Upton - Redondo Beach CA

Assignee:

TRW Inc. - Redondo Beach CA

International Classification:

H03M 100

US Classification:

341137

Abstract:

An optical analog-to-digital converter (10) that makes use of a downward-folding successive approximation conversion scheme that employs subtraction of optical signals. A pulsed optical signal (20) to be converted is applied as an input to each of a plurality of converter channels (12, 14, 16, 18), where each channel (12, 14, 16, 18) outputs one of the bits of the digital output of the converter (10). The input signal (20) to each channel (12, 14, 16, 18) is sent to a thresholding device (24, 40, 60, 80) that determines whether the intensity of the signal is greater than or less than a predetermined threshold value. The first channel thresholding device (24) compares the input signal (20) to a threshold value that is one-half of a known maximum intensity. Subsequent channel thresholding devices (40, 60, 80) compare the input signal to a threshold value that is one-half of the intensity used in the previous channel in a downward-folding scheme. If the intensity of the input signal (20) is greater than the threshold value in a particular channel (12, 14, 16, 18), then that threshold value is subtracted from the input signal (20) in each of the successive channels before being applied to the thresholding device (40, 60, 80) in that channel (14, 16, 18).