ONU Circuit Design And Signal Integrity Analysis

With the increase of edge rates and clock frequency in high-speed digital systems, the components with their bandwidth above MHz even GHz are widely used in communication, signal process system. And also they bring us the issue of signal integrity (SI). Signal would express reflection, crosstalk, delay, attenuation in high-speed interconnection. Since SI problems could make system instable, correctly dealing with SI analysis of high-speed circuit is becoming the key to successfully design PCB.Firstly in this thesis, various factors which affect SI have been present based on transmission line theory, electromagnetic field theory, mixed-mode S parameter theory. Solutions for these problems are discussed. After that, use electromagnetic simulation tools and frequency domain to analyze physically discontinuity among high-speed circuit. Find out the SI situation under encapsulation structures which contain distributed components and frequency-dependent components. Discuss the influence of via adding on transmission path, and discontinuity on return path, particularly upon cutout research. Next, from the perspective of SerDes interface, discuss differential mode, common mode and signal eye diagram of differential transmission line. Deduce the optimized method of SerDes differential interface designing.Cadence SigXplorer was used as SI simulation analysis tool, Ansoft HFSS as frequency domain hybrid S parameter of the electromagnetic field analysis tool. At last, use Cadence Allegro to finish ONU PCB layout base on above analysis data.In this paper, the practice of high-speed SI analysis and ONU circuit design process could improve the efficiency and success rate of PCB design. Meanwhile reduce design cost and risk, to achieve the optimization of circuit design. The research has important reference value for theoretical study, actual engineering application and design process improvement.