Research And Optimization Of The High Speed Connector Mini SAS HD

Nowadays,the transmission rate of digit signal is rising constantly,the rise time of digit signal is becoming shorter and shorter.Due to the Fourier transform,the rise time of digit signal was composed of multiple Sine waves,when the edge rate is higher,the highest frequency of the sine wave is higher.When the rate of digit signal is high enough,the signal is transmitted at high speed,meanwhile,conductors will have some new characteristics,such as skin effect,proximity effect and high frequency loss,all of these characteristics will affect the transmission of the signal.Therefore,requirements of high speed connector were longer just mechanical properties,but adding reliability of symbols to the high speed connector,namely the signal integrity problems.High speed connectors with good performance should guarantee that the signal amplitude and phase will not be distorted and the original signal should be transferred to the next network accurately.The issue is based on a high-speed differential connector which is using SAS3.0 as the standard,to analyze the signal integrity through a combination of theory and simulation method,and to verify the reliability of the simulation data by testing and perform optimization within the simulation according to simulation and test results.First,based on the theoretical analysis,simulation of the high-speed connector is performed in software HFSS,then review its parameters whether the parameters meet specifications.Second,TRL calibration method which has higher accuracy than SOLT,is adopted to design the test fixture and implement calibration.Third,PNA(vector network analyzer)is used to test the high-speed connector's frequency domain parameters,TDR(Time Domain Reflectometry)is used to test connector's impedance to verify the correctness of the simulation.Finally,analysis and optimization of the unusual problems of the connector in high-frequency is implemented through a comprehensive results of simulation and test.Through this study we can explain:the integrity of reference ground in the circuit and the continuity of the differential impedance of the connector is very important in the high-speed signal transmission,they have a very important impact on the quality of signal transmission.