The Research Of PCB Simulation Design And Analysis Based On Signal Integrality

With the development of electronic science and technology,the new generation electronicproducts are developed with the trend of high speed and high density.The integrality of signalbecomes more important in the high density PCB board,and it also turns out to be animportant standard to measure the quantity good or bad of the electronic products circuitsystem.Factors which influence the signal integrality are reflection、crosstalk、transmissiondelay、SSN and so on,these factors have become a problem which should be resolved chieflywhen design the high circuit.In the traditional circuit design,only the quantity of signal is usedto be care,and as the limitation of simulation analysis software,the SI simulation research onlybe located on the signal line, when the power supply and ground are be seemed as ideal(aintegrate reference plane)to simulate and calculate.Under the circumstance of low speed,thedeviation of this simplified analysis maybe is not very large,but in the high speed design,thissimplified analysis which breaks away from real situation seriously,will produce greatdeviation between real date and simulated date.Electro-Magnetic Compatibility (EMC) simulation for communication system isaprocess to simulate different kinds of EMC problem in the system reasonably and effectivelyto meet the requirement of the system designing. EMC simulation makes the exist andpotential electromagnetic interferences under control in the designing phase, it prevents theextreme high cost for the EMC problem in the last stage. Through simulating and forecastingmethod guides the design of electromagnetism compatibility in development stage to avoidbeing in traditional test modification. It is to the benefit of shortening development cycle andlowering the cost to win market chance.This dissertation is based on the high frequency noise effect, transmission line theory, thepower source or ground plane,so that we can research the PCB resonance, crosstalk,simultaneously switching noise, differential signal crosstalk and signal integrity problems.This article on the basis of the transmission line theory, analysis and research the mechanismof resonance of PCB design, crosstalk, synchronous switch on the noise and so on, set up andpower distribution system mode TDR model before the PCB design to explore powerdistribution of PCB design and the method of Via cross-layer routing. Setting up a qualifiedpower distribution system by adding decoupling capacitor and VRM to reduce the voltageamplitude produced by power/ground planar resonator, and adding ground vias around vias toeliminate crosstalk produced by Via the transmission line. Then buliding board and chip model to simulate to acquire interfere data information of PCB board signal transmission andPower network produced by simultaneously switching noise, resonance voltagedistribution,and crosstalk. BY adding shunt capacity, impedance matching and filter to reduceelectromagnetic interference produced by simultaneously switching noise, crosstalk, reflex totransmission signal and the system. Optimizing resonance system work area by addingdecoupling capacitor and sharing common ground plane, importing IBIS chip model indesigner to emulate simultaneously switching noise, reducing interference withsimultaneously switching noise by adding shunt capacity. At last, this article establishes theequivalent circuit model with the designer/Nexxim software to conduct time domainsimulation, optimizes power distribution network and signal transmission network of the PCBaccording to the simulation result, and makes the PCB with good power integrity and signalintegrity.