Samtec Final Inch PCIE Series Connector Differential Pair Configuration Channel Properties

Transcription

1 Samtec Final Inch PCIE Series Connector Differential Pair Configuration Channel Properties Scott McMorrow, Director of Engineering Jim Bell, Senior Signal Integrity Engineer Page 1

2 Introduction and Philosophy The Final Inch is not complete without validation of the electrical system performance through signal integrity modeling, simulations and measurements. Advanced 2D and 3D modeling methods are used to provide accurate models for all sections of the Final Inch boards. The PCI Express connector model has been developed through Samtec s advanced modeling process, as found at Three dimensional PCB structures, such as SMA launches and vias, are modeled using a combination of CST Microwave Studio and Sigrity BroadBand SPICE. Two dimensional PCB traces are modeled using Ansoft Maxwell 2D FEM Field Solver and Synopsis HSPICE w- element table models. All modeled elements are combined and simulated using Synopsis HSPICE. Page 2

3 PCB Stackup and Trace Configuration 4 layer construction Outer layer microstrip routing. 5 mil trace width 57 ohm characteristic impedance (single ended) 100 ohm differential impedance Er = 4.1 Loss Tangent = Page 3

4 PCB Stackup and Trace Configuration PCB 2 Measurement Point Stimulus Launch PCIe Uncoupled Lossy Traces PCB 1 Page 4

5 Eye Pattern Configuration Signal stimulus +/- 400 mv Driven victim and aggressor signals terminated differentially to 100 ohms. Eye simulations performed with worst case adjacent neighbor pairs switching at maximum bit rate and driven victim switching with a pseudo random pattern. Page 5

6 Insertion and Return Loss Configuration Victim Input Stimulus - 1 Volt a.c., linearly swept from 100 MHz to 10 GHz Victim Signal terminated at measurement point, 50 Ohms to Ground. Passive Signals terminated at both end points, 50 Ohms to Ground Page 6

7 Eye Channel Properties PCIE Edge Card Fingers A A V V A A Card edge V = Victim pair A = Aggressor pair = Signal = Grounded connector pin Page 7

8 Eye Channel Properties Differential, 1.0 Gbps, 50 ps not active active Page 8

9 Eye Channel Properties Differential, 1.0 Gbps, 50 ps not active active Page 9

10 Eye Channel Properties Differential, 2.5 Gbps, 50 psec not active active Page 10

11 Eye Channel Properties Differential, 2.5 Gbps, 50 psec not active active Page 11

12 Eye Channel Properties Differential, Gbps, 50 psec not active active Page 12

13 Eye Channel Properties Differential, Gbps, 50 psec not active active Page 13

14 Eye Channel Properties Differential, 5.0 Gbps, 50 psec not active active Page 14

15 Eye Channel Properties Differential, 5.0 Gbps, 50 psec not active active Page 15

16 Eye Channel Properties Differential, 10.0 Gbps, 50 psec not active active Page 16

17 Eye Channel Properties Differential, 10.0 Gbps, 50 psec not active active Page 17

18 Eye Channel Properties Differential, 12.5 Gbps, 50 psec not active active Page 18

19 Eye Channel Properties Differential, 12.5 Gbps, 50 psec not active active Page 19

20 Loss Channel Properties A A V V A A Card edge V = Victim net P = Passive net, terminated at both ends, 50 ohms to Ground = Signal = Grounded connector pin Page 20

21 Insertion Loss Channel Properties Differential db vs. Frequency Page 21

22 Insertion Loss Channel Properties Differential % vs. Frequency 100% 80% Percent 60% 40% 20% 100% 80% Percent 60% 40% 20% Page 22

23 Return Loss Channel Properties Differential db vs. Frequency Page 23

24 Return Loss Channel Properties Differential % vs. Frequency 45% 40% 35% 30% Percent 25% 20% 15% 10% 5% 0% Percent 45% 40% 35% 30% 25% 20% 15% 10% 5% 0% Page 24

25 Crosstalk Channel Properties A A V V A A Card edge V = Victim net A = Aggressor net = Signal = Grounded connector pin Page 25

26 Crosstalk, Differential Pair Aggressor - Victim - Passive db vs. Frequency Red = NEXT Blue = FEXT Page 26

27 Crosstalk, Differential Pair Victim Aggressor - Passive 14% 12% 10% % vs. Frequency Red = NEXT Blue = FEXT Percent 8% 6% 4% 2% 0% 14% 12% 10% Percent 8% 6% 4% 2% 0% Page 27

28 Crosstalk, Differential Pair Aggressor - Victim - Aggressor db vs. Frequency Red = NEXT Blue = FEXT Page 28

29 Crosstalk, Differential Pair Aggressor - Victim Aggressor 14% 12% 10% % vs. Frequency Red = NEXT Blue = FEXT Percent 8% 6% 4% 2% 0% 14% 12% 10% Percent 8% 6% 4% 2% 0% Page 29

30 Crosstalk, Differential Pair NEXT Comparison db vs. Frequency Red = Aggressor- Victim-Passive Blue = Aggressor- Victim-Aggressor Page 30

31 Crosstalk, Differential Pair NEXT Comparison 14% % vs. Frequency 12% 10% Red = Aggressor- Victim-Passive Percent 8% 6% Blue = Aggressor- Victim-Aggressor 4% 2% 0% 14% 12% 10% Percent 8% 6% 4% 2% 0% Page 31

32 Crosstalk, Differential Pair FEXT Comparison db vs. Frequency Red = Aggressor- Victim-Passive Blue = Aggressor- Victim-Aggressor Page 32

33 Crosstalk, Differential Pair FEXT Comparison 14% % vs. Frequency 12% 10% Red = Aggressor- Victim-Passive Percent 8% 6% Blue = Aggressor- Victim-Aggressor 4% 2% 0% 14% 12% 10% Percent 8% 6% 4% 2% 0% Page 33

34 PCIE Series Final Inch Test Case - Conclusions The PCIE Series (PCI Express) connector pair shows excellent performance in simulated applications between 1 and 12.5 Gbps. Page 34