Design And Realization Of GPON OLT Optical Transceiver Module

With the rapid development of modem communication network, higherbandwidth of access network is required. Because of its advantages such as high datarates, high efficiency and flexibility, GPON (Gigabit-capable Passive Optical Network),which uses the rich bandwidth of optical fiber, is regarded as an optimal solution forthe "last mile" bottleneck of access bandwidth. However, by reason of immaturetechnology, high cost and many other disadvantageous factors, GPON system is stillnot able to be applied widely. To solve this problem, a GPON OLT TransceiverModule and its related technology are discussed, which is the key device of GPONsystem. And the solution of this GPON OLT module is proposed, including thetransmitting and receiving segment. According to the solution, integrated ICs are usedto realize the hardware design.Main researchs of thesis is as follows:(1) The thesis researchs on the ITU-T G.984 protocol standards, and analyzes thedata packet structure and code-model features of GPON system, summarizesdifficulties and the existent problems in GPON OLT module design.(2) Base on an analysis of burst-mode receiving technology, and consider theperformance of receiver sensitivity, bit error rate, bandwidth, dynamic range anddesign costs, AC-coupling burst-mode receiving and DC-coupling burst-modereceiving solution are proposed. The AC-coupling solution improves traditionalreceivers, fixes the AGC of TIA, chooses the suitable AC-coupling capacitance,imports high-speed switch to help coupling capacitance discharge fastly during guardtime; The DC-coupling solution adopts feed-forward automatic threshold contrel loop,uses the outside Reset signal provided by MAC to reset ATC circuit fastiy and tomeet the requirement of burst-mode.(3) According to the different performance parameters and function of ICs suchas Philips's TZA3046, Micrel's SY88903, VITESSE's VSC7718 / VSC7728, andMaxim's MAX3735 / MAX5026, the schematic diagram and PCB layout of the transmitting and receiving segment of module are both realized, as well as samples ofthe module's hardware and software debugging.(4) The samples of modules designed by this thesis have been tested allparameters during all temperature range, in test system platform of burst-modereceiving and continue-mode transmitting. The test result shows that the GPON OLToptical transceiver module realized by this thesis meet the ITU-T G.984.2 protocol,the AC-coupling solution reduced design costs, and the DC-coupling solution realizedmuch better performance. The samples of module have passed the testing incustomer's GPON testing system, and are used in actual GPON network.