As presented at Euro DesignCon 2004 Channel Compliance Testing Utilizing Novel Statistical Eye Methodology

Transcription

1 T10/05-198r0 As presented at Euro DesignCon 2004 Channel Compliance Testing Utilizing Novel Statistical Eye Methodology Anthony Sanders Infineon Technologies Mike Resso John D Ambrosia Technologies Agilent Technologies Tyco Electronics Presented by Harvey Newman Infineon Technologies To SAS-2 2 6Gbps physical WG May 25, 2005

2 A Simple System Perspective Receiver

3 Current Methods ( f ) 20 ( e)[ a f + a f a f ] S 21 log SDD21 (db) ISI Loss > 4 db Sample Compliance Interconnect

4 The Real Problem Sdd21 (db) Frequency (GHz) Top Near-Top Near-Bottom Bottom XAUI

5 How to Measure The Channel Physical Layer Test Test System software Tyco Tyco Backplane 4-4-port Vector Network Analyzer

6 Measuring the whole Channel Term. Forward Channel Term. P1,P2 TxP,N P3,P4 RxP,N Term. Term. NEXT Term. Term. Term. Term. Term. Term. P1,P2 TxP,N FEXT P1,P2 TxP,N P3,P4 RxP,N P3,P4 RxP,N Term. Term.

7 Differential Measurements Differential Signal Common Signal Port 1 Port 2 Port 1 Port 2 S DD11 S DD12 S DC11 S DC12 S DD21 S DD22 S DC21 S DC 22 S CD11 S CD12 S CC11 S CC12 S CD21 S CD22 S CC21 S CC 22

8 Frequency Response 0-5 Return Loss Channel Return Loss Transmitter & Receiver -10 Magnitude (db) Transfer Function with return loss Example crosstalk Frequency (Hz) x 10 9

9 Analysing Channels Must include all channel effects Mode conversions Channel and device return loss Crosstalk Magnitude and phase Return Loss Influence of the pattern/coding Must include all jitter and statistical effects

10 What is the real problem? Various Coding FIR Various Coding FIR Linear equalisation Multilevel sampling Nonlinear equalisation Transmitter Channel Receiver Correlated and uncorrelated transmitters Various Channels incl. FEXT and NEXT Various jittered signalling types with common mode noise and return loss

11 Introducing Stateye Following slides introduce the basic theory of stateye based on alpha c++ code and gnuplot running under Linux I would suggest that if there are questions, ask while I am presenting. It is important to understand each step

12 Simple Transfer Function

13 Impulse Response

14 Pulse Response

15 Symbols

16 ISI

17 Worst case patterns

18 Worst Case Sampling Jitter Jitter Probability Density Function

19 Worst Case Eye Opening Jitter Probability Density Function

20 Cursor Extraction

21 Conditional pdf

22 Conditional pdf

23 Conditional pdf

24 Sampling Jitter

25 Average pdf over transmit jitter

26 Pdf -> > cdf

27 Conditional Average cdfs

28 Stateye

29 Taking more cursors

30 Taking more cursors

31 Simple Crosstalk

32 Pulse Response of Crosstalk

33 Effect of crosstalk on pdf

34 Effect of crosstalk on stateye

35 Multiple Crosstalk Aggressors

36 Multiple Crosstalk Aggressors

37 Real Probability

38 Pause for Breathe (mine)

39 A Channel Example

40 Short Channel no via

41 Short Channel no via

42 Short Channel no via

43 Short Channel with via

44 Short Channel with via

45 Short Channel with via

46 Longer Channel

47 Longer Channel

48 Longer Channel

49 Longer Channel + deemphasis

50 Longer Channel + deemphasis

51 Long Channel with close rx via

52 Long Channel with close rx via

53 Long Channel with close rx via

54 Longer Channel + DFE

55 Longer Channel + DFE

56 Dealing with Correlated Data

57 DCD or Pulse Shrinkage

58 PAM

59 Return Loss, Boosting and FIRs Transmitter n port s-parameter Channel n port s-parameter Linear Equaliser Receiver n port s-parameter Convert to T-matrix, multiply and convert back to S-matrix Calculate pulse response Push pulse response through any FIR

60 Dealing with common mode Calculate common mode transfer function Create the pulse response seen at the receiver Extract the cursors Additional use the cursors in the calculation of the conditional pdf,, as for crosstalk

61 Stateye Stateye is a non-profit, open source, developers forum under stateye.org Currently stateye is being re-developed Stateye is being rewritten currently under c++ to allow easier contribution and exploration of differing technical opinions The initial c++ class structure and initial functions will be made available at the above website.

62 Stateye Lab results concerning validation of this technique are also available from the website Stateye is under continuous development and improvement and encourages contribution This presentation is available from the T10 website. T10/05-198r0