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Proceedings Paper

Line Terminal Circuit Module Design For Fiber Optic Digital Subscriber Loops
Author(s): Toshiyuki Tsuchiya; Koh-ichi Suto; Etsugo Yoneda
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Paper Abstract

Design philosophy of a fiber optic transmission line terminal circuit (LTC) module for digital subscriber loops is described. A small, cost effective LTC module has been developed that realizes a 52 to 156 Mb/s fiber-to-the-home system. The salient points are ; various combinations of LDs and PDs/APDs can be used to match the subscriber line length requirements, CMI or scrambled NRZ line codes can be used, the module is suitable for single mode fiber (SMF) or graded index fiber (GIF) cables, high density LSI techniques can be used to develop single chip components. The volume of the contructed module is 92.6cm3 with a dispersion power of 3W. A single low power IC chip has been developed that includes decision and timing circuits. Thus timing phase adjustments are not needed. Differential amplification created between the pre-amplifer IC and the main amplifier IC is employed to yield a high common mode rejection ratio and suppress the effects of external noise. The double loop of the auto-power-control (APC) for the LD is adopted to separately control the d.c. bias current (Is) and the pulse modulation current (Ip). The CMI-CODEC-IC is fabricated by a Bi-CMOS process. It includes a PLL circuit that doubles input clock frequency for CMI signal coding. The CMI line code can be adopted to maintain bit sequence independence, facilitate hardware implementation of the timing-extraction circuit, and prevent bit errors caused by received optical power fluctuations. Received optical power fluctuations can happen when fibers are manually handled during cable installation or mid-span branching.

Paper Details

Date Published: 15 January 1990
PDF: 15 pages
Proc. SPIE 1179, Fiber Networking and Telecommunications, (15 January 1990); doi: 10.1117/12.963391
Show Author Affiliations
Toshiyuki Tsuchiya, Yokosuka Research and Development Center, N.T.T. (Japan)
Koh-ichi Suto, Yokosuka Research and Development Center, N.T.T. (Japan)
Etsugo Yoneda, Yokosuka Research and Development Center, N.T.T. (Japan)

Published in SPIE Proceedings Vol. 1179:
Fiber Networking and Telecommunications
Joseph Garodnick; Lynn D. Hutcheson; David A. Kahn, Editor(s)

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