A Burst-Mode Bit-Synchronization IC With Large Tolerance for Pulse-Width Distortion for Gigabit Ethernet PON Hitoyuki Tagami, Seiji Kozaki, Kenich Nakura, Shigeki Kohama

Abstract

A burst-mode bit-synchronization IC applied to the upstream transmission in a gigabit Ethernet passive optical net- work (PON) was experimentally verified to have a large tolerance for pulse-width distortion within 0.66 UI. The extra tolerance of 0.22 UI over the IEEE 802.3ah specification can be assigned to additional distortion generated at an optical receiver incorpo- rated into an optical line terminal. Such a large tolerance was at- tained by precisely generated eight-phase clocks based on theoret- ical analyses of distortion tolerance considering real circuit param- eters and by an enhanced data selector incorporating a pulse-width detector to monitor the pulse-widths of isolated bits. The IC de- veloped includes a burst into series transformer to permit connec- tion to commercially available PON LSI developed for serial data transmission in Ethernet systems. The theoretical study into the numbers of allowable bit errors and consecutive pattern matches in byte synchronization established following two conditions: 1) al- lowable error more than one bit in synchronization pattern with 10-bit length was required to hold the synchronization loss rate to less than a few times per year and 2) consecutive pattern matching more than twice was required to hold the synchronization error rate to less than a few times per year.