Signal Integrity Design Of USB 3.1 Connector System

With the development of communication technology,the transmission rate of signal becomes faster and faster,especially in recent years,the rapid development of 5g related technology makes the whole society gradually enter the intelligent society.With the characteristics of high speed,low delay and large connection,5g era has higher requirements on the performance of connector.With the increase of signal frequency and transmission rate,there will be a series of signal integrity problems,such as reflection,crosstalk,skin effect and so on,which will affect the reliable transmission of signals.This paper takes USB 3.1 connector system as the research object.Firstly,it introduces the relevant theoretical knowledge of signal integrity,including the learning of transmission line theoretical knowledge,the formation of skin effect,the concept of differential pair and the classification of signal integrity problems.Then,the USB-A connector is briefly introduced.In order to ensure the quality of signal integrity,a good physical model must be established to ensure the reliability of the connector model.For each component of the connector,including uniform transmission line,contact area,insulation layer and shell,the paper makes a detailed modeling design and analysis.Through the theoretical verification after modeling,the impedance value and transmission time of the connector are verified to ensure the reliability of the model based on USB-A connector.Next,from the goal and scheme of simulation,select the appropriate simulation software.The three-dimensional electromagnetic simulation software CST is used to set the parameters before simulation,select the solver,set the coaxial port and waveguide port,and get the loss and crosstalk curve of the connector.The S-parameter standard file generated by the former is imported and processed by the circuit simulation software ads.the TDR characteristic impedance and eye diagram are obtained by combining the signal source,receiver and transmission line model in the circuit schematic diagram.The simulation results all meet the requirements.Because the impedance of connector 2.0 spring is at the required edge,the impedance of connector 3.0 spring is generally lower,so it is necessary to optimize.Finally,the USB-A connector is optimized.The TDR impedance of the spring can be improved and the transmission performance of the connector can be improved by gradual optimization of the contact part of the spring at the male end,reducing the length of the stump to 0.2mm and hollowing out the local air medium in the contact area,After optimization,the impedance increases by about 3 Ω.The insertion loss and return loss also meet the requirements before and after optimization;When the length of the residual pile is reduced from 0.8mm to 0.2mm,the TDR impedance,insertion loss and return loss change significantly.The maximum increase of TDR impedance is 4.5 Ω,The impedance increased significantly.The optimized insertion loss and return loss are also better,which means that more signals are transmitted;The TDR impedance will be larger if the medium of the differential reed in the contact area is partially hollowed out and directly contacted with the air.In the actual design,the medium near the reed in the contact area can be hollowed out to match the impedance,reduce the reflection and improve the quality of the signal.