statistical eye simulation requirements - ibis · using convolution method. ¾simulation platform...

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HUAWEI TECHNOLOGIES CO., LTD. Page 1 27. Aug. 2006 HUAWEI TECHNOLOGIES Co., Ltd. Security Level: Statistical Eye Simulation Requirements Huang Chunxing [email protected] Asian IBIS Summit, Shanghai China October 27, 2006

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Page 1: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES CO., LTD.Page 1

27. Aug. 2006

HUAWEI TECHNOLOGIES Co., Ltd.

Security Level:

Statistical Eye Simulation Requirements

Huang [email protected]

Asian IBIS Summit, Shanghai ChinaOctober 27, 2006

Page 2: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 2

Statistical Eye Simulation Flow

Data Source

Emphasis

Jitter Modulation

Forward Channel

Equalizer

1、Calculating PDF of Fwrd Pulse Reponse 2、Calculating PDF of Xtlk and Convoluting with Fwrd PDF3、Generating RJ distribution and computing overall PDF 4、Drawing Statistical Eye and Bathtub

Xtlk Channel 1 Xtlk Channel N

Equalizer Equalizer

……

Statistical processing

Transient Simualtion

Simulation flow:

Time domain simulation

Statistical post-processing

The data source could be signal source or real serdes model.

Page 3: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 3

Simulation Requirements

Simulation platform should support IBIS or Hspice serdesmodel.

Simulation platform should simulate channel responses by using convolution method.

Simulation platform should easily realize jitter modulation, equalizer and emphasis.

Simulation platform should support equalizers, such as LFE, DFE and CTE.

Powerful post-processing ability.

Simulation platform may further support co-simulating with Matlab for user defined statistical processing.

Page 4: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 4

Pattern Generator Voltage Controlled Delay

Sinusoidal Source

DCD

signal with Jitter

Jitter Modulation

Using Voltage Controlled Delay to add jitter

Jitter at transmitter includes PJ, DCD

RJ will be consider in statistical post-processing

∑=

+=N

iiiitotal twAtPJ

0

)cos()( θ

)]2/()2/([*5.0 WxWxDCD ++−= δδ

Page 5: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 5

Emphasis

Emphasis technique includes pre-emphasis and de-emphasis

Both pre-emphasis and de-emphasis could be expressed as FIR filter

0 0.1 0.2 0.3 0.4 0.50

0.5

1

1.5

2

2.5

3

3.5

4Frequency Response

Normalized

dB

Page 6: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 6

Channel ModelsChannel models, including fwrd and xtlks, could be expressed in S-parameter

Supporting transient simulation with touchstone files

pulse response

Impulse response

Page 7: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 7

Equalizer-LFE

)(*)(*)(*)( 112010 −− +++= NinNinin TVWTVWTVWTV L

Input

Output

……

WN W2 W1

+

T T

LFE is linear feed-forward equalizer

discrete – usually just one tap per bit

finite – not long enough to completely correct the impulse response

May result in noise gain

Page 8: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 8

Equalizer-DFE

Slicer Input

Output

T ……

W1 WN-1 WN

T T

)(*)(*)(*)()( 221100 NNin TDWTDWTDWTVTV −−− −−−−= L

DFE is decision feed-back equalizer

DFE uses a feedback loop of the desired signal which

is decoded from the output of a slicer

DFE can further correct the residual ISI

Page 9: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 9

Equalizer-CTE

CTE is continuous time equalizer

CTE model is an ideal circuit with

the desired pole, zero response.

p0 and z0 are programmable

)()()(

0

0

0

0

pszs

zpafHCTE +

+=

Page 10: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 10

Equalizer-Algorithm

Calculating the optimal sampling point and equalizer coefficients

LMS adaptive algorithm

Zero Forcing algorithm

Page 11: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 11

Statistical Post-processing

Calculating Forward channel PDF

1.Overlapping each bit at one UI range.

2. At each UI sampling point, computing

PDF of Overlapping data.

Zero

Amplitud PDF at each point

Page 12: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 12

Statistical Post-processing

Xtlk Convolution Method

1.Interpolating each Xtlk channel responses to small enough time interval

2. Overlapping each bit in one UI range

3. Computing PDF of Overlapping data at each UI sampling point

4. Averaging PDFs through whole UI sampling points to get the average PDF.

5. Repeating 1-4 for each aggressors.

6. Convolving average PDFs of all aggressors to get the whole crosstalk PDF.

Charles Moore presented convolution method in his paper “Computing effect of cross talk using Convolution” at 802.3ap.

http://grouper.ieee.org/groups/802/3/ap/public/channel_adhoc/moore_c1_0305.pdf

Page 13: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 13

Statistical Post-processing

Zero

Amplitud PDF at each point

Signal PDF

Random Jitter

Random Jitter distribution

Overall PDF

∫∞

∞−

⋅+= υυυττ dPISIPISIP RJ )(),(),(

2

2

2

21 σ

σπ

t

RJ eP−

=

Page 14: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 14

Statistical Post-processingStatistical Eye

Statistical eye is set of probability contours

Horizontal axis is with respect to sampling point

Vertical axis is with respect to signal amplitude

Different colored lines represent BER

Page 15: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 15

Statistical Post-processingBathtub

Intercept through statistical eye along horizontal axis to get horizontal Bathtub at definite voltage

Intercept through statistical eye along vertical axis to get vertical Bathtub at definite sampling time

Horizontal

Vertical

Page 16: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 16

Overall Simulation Eye Flow

Channel

Eye after Equalizer

Transmitter Eye

Eye after Jitter Modulation

Eye after Emphasis

Eye after Channel

Page 17: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 17

Example - Channel pre-simulationAssumed conditions:

10Gbps NRZ, PRBS 23, 100000 bits, amplitude 800mvpp, Tr(f) = 24ps

0.15UIpp DJ = 0.05UI DCD+0.1UI PJ, 0.15UIpp RJ @10-12BER

BER = 1e-12 (2*Q=14.069)

3tap de-emphasis, 5tap DFE

Slice voltage: 10mV

Forward Channel Eight crosstalk channels

Page 18: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 18

Example - Channel pre-simulation

Time Offset (UI)

Am

plitu

de

Statistical Eye=0.028, Width=0.222

0 0.2 0.4 0.6 0.8 1-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

1

2

3

4

5

6

7

8

9

10

11

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-12

-10

-8

-6

-4

-2

0

Time Offset (UI)

BE

R

Bathtub at threshold=0.010

Simulation result:

28mv eye-height

0.222UI eye-width

It shows that the channel could undertake 10Gbps data transmission

Page 19: Statistical Eye Simulation Requirements - IBIS · using convolution method. ¾Simulation platform should easily realize jitter modulation, equalizer and emphasis. ¾Simulation platform

HUAWEI TECHNOLOGIES Co., Ltd. Page 19

Conclusion

Basic method of statistical eye simulation has been presented here

An ideal platform to realize statistical eye simulation:Jitter Modulation at transmitter

Pre-emphasis or de-emphasis

Supporting Forward channel, Xtlk channel models

Equalizer

Statistical post-processing