The Prediction And Cancellation Technology Of Electromagnetic Noise In Multiconductor Transmission Lines

As an important element connecting electrical and electronic equipment,multiconductor transmission lines(MTL)occupy a position that cannot be ignored.However,the crosstalk problem brought by unintentional coupling of electromagnetic energy has been the main source of electromagnetic interference(EMI)of MTL.As one of the two kind crosstalk,far-end crosstalk(FEXT)influence the next level equipment of the system,and it can affect the normal transmission of the signal and cause reliability reduction and function failure of the system under serious circumstances,which attracts a lot of research attention to FEXT cancellation.At present,researchers focus on coupling mechanism,filtering and compensation method of FEXT,but researches on these aspects still need to go further.In this paper,taking MTL as research object,a series of studies have been carried out including:1.The extraction method of electromagnetic parameters of MTL is proposed.Based on the hypothesis of transverse electromagnetic(TEM),the transverse electrostatic field model and the harmonic magnetic field model are established.Based on these models,the electromagnetic parameters are extracted by ANSYS software.Besides,the extraction method are verified by the input impedance characteristics experiment of a double-conductor transmission line.2.The MTL equations are derivated and solved,and the characteristics and influence factor of FEXT are analyzed.Based on the MTL model,the MTL equations are derivated,the general solution of the equations is obtained by modulus conversion method and the special solution is obtained combined with terminal conditions.According to the special solution and the electromagnetic parameters,the distribution of victim lines' FEXT influenced by the number and phase shift of aggressor lines' excitation source is analyzed.Then several influence factors of FEXT are analyzed: the distance between aggressor line and victim line has a great influence on FEXT,the height of lines has little influence changes and FEXT changes with electrical size alone but not length or frequency.3.Passive circuit network integrated in terminal to cancel FEXT is proposed.The coupling of electromagnetic energy can be divided into two kind of coupling: capacitive coupling and inductive coupling,both of which have their characteristics.By analyzing the mechanism of two kind of coupling,the total crosstalk formula can be obtained.Based on that,RC circuit,RL circuit and RLC circuit is proposed to structure the compensation crosstalk signal network,which is verified by experiments following.4.A partial phase shift network(PPSN)cascaded in MTL to cancel FEXT is proposed.The MTL can be regarded as a multiport network if local details are ignored.Further analysis discover that,two segments of MTL cascaded by PPSN,which will make voltage phase shift of aggressor lines but do nothing with victim lines,can cancel the FEXT to a certain extent.Simulations and experiments are carried out to verify its effectiveness,besides,the characteristics of phase shift angle and length ratio of two segments are analyzed.