Research On Very Short Reach Optical Transmission System

With the development of the networks capacity, more and more network devices are put together in the service provider's office. Most of these devices are connected by the optical link in very short distance. The former long haul optical link scheme is not suitable under this condition because of high price. Thus the very short reach (VSR) optical transfer scheme comes out. The implementation and improvement of the VSR technology are shown in this paper. The overall structure of the system is shown at first. Then the design of key module-signal transformer module is shown. According to the top-down methodology, the designs the logic circuits of the transmitter and receiver are shown. The sub blocks include the substitutions of the framer limiter, data mapping and alignment module, the First In First Out module, the loss synchronization and lose framer state machine, the 8B/10B coder decoder, the Cyclic Redundancy Check module, the double data rate circuit and so on. Then, the entire circuit module is optimized by the logic circuit optimization methods and the proper routing of the whole module. By using the logic lock method provided by the vendor and soft, the performance of the design is optimized step by step. Then a novel switch protecting method is proposed based on the analysis of the signal format. The performance of this method is analyzed, the result shows that it improve the system reliability greatly. The design of the print board circuit of the VSR system is shown next. the high speed digital phenomena, signal integrity,electromagnetic compatibility, are expatiated in detail. The mechanism and solution of reflection,crosstalk,ringing, especiall the teminal of the low voltage differential signal, are also given. The overall scheme and circuit routing design of the system are shown. Finally, the satisfied test result and analysis of the system is shown. The improvement and extensional application of current sytem is also discussed in the end. Keywords: very short reach, parellel optical transimition, dignal transform, test board...