| In recent years,due to the rapid growth of communication technology,the speed of data transmission is getting faster and faster.Connector is an important part of electrical connection,which is used in all fields of electrical engineering and all kinds of electronic products.In previous transmission systems,the signal transmission rate is relatively low,and the interconnected system constructed by the connector is transparent with respect to the transmitted signal.This system only plays the most basic connection role,and will not affect the signal transmission quality.However,with the continuous improvement of signal transmission rate,distributed conductance,distributed capacitance and distributed inductance appear in the circuit.the flow of the current in the wire exhibits skin effect,and the distributed parameter effect exists on the transmission line,thus the circuit should be regarded as the distributed parameter circuit.This change will affect the reliable transmission of signals,which leads to the study of signal integrity.Differential transmission system has been widely used in high-speed interconnection systems because of its strong anti-interference ability and precise timing control.The research on signal integrity of high-speed connector using differential transmission is of great significance for the reliable transmission of signals in high-speed interconnection system.On the basis of transmission line theory and signal integrity research,a high-speed connector with transmission rate up to 10Gbps and differential transmission is selected to study its signal transmission performance.In this paper,the characteristic impedance,insertion loss,near end crosstalk and far end crosstalk and other performances are studied respectively by means of modeling and simulation and theoretical calculation.It has been proved that the simulation method for this connector are reasonable,and the simulation results are consistent with the given indexes.After confirming that the simulation method is correct,the connector still needs to be tested.In this project,the vector network analyzer,a measurement instrument in the frequency domain,is selected.The signal generator of this instrument can scan the frequency of the measured parts in a frequency band.At the same time,this instrument has a strong error calibration function.In order to keep PCB fixture,connection cable and other parts transparent to the test process,TRL calibration method was selected to eliminate the system error before the test,and the signal integrity of PCB fixture was tested to check whether it is qualified.Combined with the final test results and simulation results,it is determined that the simulation test method based on the original model can provide a more systematic analysis for the signal integrity of high-speed connector.Manufacturing tolerance is essential in actual production.According to the given tolerance range,on the basis of the above work,this topic respectively analyzed the influence of the changes of differential inner spacing,differential line width,medium thickness and dielectric constant changes on the signal integrity performance indicators.After finding out the parameters that may affect the signal integrity performance,this project optimizes the connector within the tolerance range.According to a series of analysis,this project finally determined the optimal scheme,that is,reduce the difference internal spacing and increase the difference line coupling strength.This scheme improves the insertion loss,near-end crosstalk and far-end crosstalk of the connector by about 3%,and achieves the expected goal.The work done in this paper lays a foundation for the future research on signal integrity of high speed connectors using differential transmission.The optimization method adopted in this paper can provide important reference for high-speed PCB design,and provide help for fault location and problem solving in engineering. |
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