Research On The Near-field EMI From PDN In High-speed Digital Circuit

The circuits are tended to be large scale, small size and high-speed. Theproblems of signal integrity and power integrity are becoming increasingly seriousin high-speed digital circuit. With the circuits brcoming high density, high speed andhigh power, the high-speed interconnect lines become increasingly vulnerable tointerference, including interference between signal lines and power distributionnetwork. The complexity of power supply makes the interference of powerdistribution network more and more serious. Designers rely on experience to solvethe problems in many cases. So there will be crosstalk which lead to the instabilityof high-speed system. Therefore, the research on the near-field interferencemechanism of the power distribution network and interference suppressiontechnology has theoretical significance and application value.Firstly, analysis the mechanism of noise sources in synchronous Buck converterwhich is commonly used in high-speed circuit, analysis the near-field interferencebetween the power distribution network and the signal lines using the transmissionline and crosstalk theory. Provides a theoretical basis for the quantification modelingand simulation.Secondly, builds the high frequency model of the synchronous Buck converterusing Saber, and by comparison with the converter noise of the actual PCB board,the high frequency noise model is proved right. At the same time, creates near-fieldinterference models of the power distribution network using the field-circuitco-simulation technology, including the signal lines near-field interference modeland LVDS near-field interference model. Simulates models using the standardsquare wave as noise and summarys the rules. And leads the actual noise into thesimulation, by comparison with the interference noise of the actual PCB board, thenear-field interference models are proved right.Finally, uses three methods to suppress the power supply noise, uses stackeddesign and the safe spacing design to suppress the near-field coupling of distributionnetworks, and they have a good performence.This paper analyzes the interference mechanism of high-speed signal from thepower distribution network, and introduces methods to suppress the interference.Provides references to the high-speed signal designer to solve problems of signalintegrity caused by switching power supply. At the same time, builds the simulation model of power distribution network using field-circuit co-simulation method,provides reference for high-speed digital circuit design.