Design Of The Converter Integrate Circuit In VSR4-3.0 System

Very short reach (VSR) is an optical transmission technology to transmit data over a short distance (about 300m~600m). It is mainly used to link two equipments of different network layers,such as Switch,CR,OXC,ADM and WDM terminals. It has the advantage of easy constructing,stable performance and low cost. OIF-VSR4-3.0 is a parallel optical transmission interface with 4 channels to transmit and another 4 channels to receive the STM-64/OC-192 frame over'very short'distances. It only needs one 12-fiber cable to implement bidirectional transmission. The size of its device is smaller. So it has a good development prospect.In this paper, OIF-VSR4-3.0 parallel optical transmission protocol is deeply studied. The converter IC of VSR system according to this standard is designed, and implemented by using FPGA. With the blocking design method, codes of some function modules are compiled with Verilog hardware description language, such as frame aligner module, frame synchronization module and channel skew remove module. On the base of the characters of STM-64/OC-192 data through the 4 data channels,and the requirement of G.783 recommendation to the SDH frame synchronizing performance, key parameters are chose by calculating and analyzing. Altera's development kit Quartus II5.0 is used to complete logic synthesis & optimization, placement & routing, timing simulation, and timing analyzer of all the circuits.Some advices are given to optimize the operation of the converter IC. One bit error-tolerance technique is analyzed to enhance the detection velocity and the reliability of the frame synchronization system. Gray code technique is used in frame orientation counter to solve the burr problem. Pipelining design method is introduced in large-scale Multiplexer to raise the circuit frequency.All designs in this paper are realized using EP1SGX25F1020C7 FPGA of Altera Stratix GX series. The structures and simulation results of modules are presented. Through the results, we can draw the conclusion that all of the designs can correctly implement their functions and meet the requests of 10Gbit/s high-speed parallel optical transmission system.