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Welcome for HSD Success in the Multigigabit/s Era Dr. Hany Fahmy, Master High-Speed-Digital Application Expert Agilent EEsof EDA April 25 th , 2012 1

Backplane hsd meeting_may_8th_2012_sharable

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Page 1: Backplane hsd meeting_may_8th_2012_sharable

Welcome for HSD Success in the Multigigabit/s Era

Dr. Hany Fahmy, Master High-Speed-Digital Application Expert

Agilent EEsof EDA

April 25th , 2012

1

Page 2: Backplane hsd meeting_may_8th_2012_sharable

High-Quality Assurance of Success

• EEsof rides the wave of HSD by wearing the shoes of the HSD

Designers

• Don’t provide “JUST-TOOLS” but Provide “DESIGN-WORKFLOW”

• Understands the “Pain” our Customers in designing Multigigabit

Technology

• Strive to Adapt the needs of our Customers through “Continuous

Improvement” of our Design-Flow

May 8, 2012

Confidentiality Label

2

Page 3: Backplane hsd meeting_may_8th_2012_sharable

Design and Analysis of ATCA 14-Slot Dual

Star 10G ETHERNET Backplane

10GBps per lane (10x10 100GBps)

Towards 25GBps per lane (4x25 100GBps)

May 8, 2012

Confidentiality Label

3

Page 4: Backplane hsd meeting_may_8th_2012_sharable

Agenda

08.05.2012 4

1) Simulation Setup for the Blade

2) I/O driver Setup

3) Blade-2-Blade Investigation

5) Blade-2-Backplane-2-Blade Investigation

6) Backplane Via Structure Sensitivity Analysis and Optimization

7) Conclusion

4) Simulation Setup for the Backplane

Page 5: Backplane hsd meeting_may_8th_2012_sharable

Simulation Environment: Blade

Lanes routed TOP-2-Bottom &

TOP-2-Inner

08.05.2012 5

TOP-2-Bottom routing channel

TOP-2-Inner (L10/L12) routing channel

Page 6: Backplane hsd meeting_may_8th_2012_sharable

Building blocks of the Blade

IC Package: coupled model w BGA Balls

08.05.2012

6

Page 7: Backplane hsd meeting_may_8th_2012_sharable

Stackup Parameters for the Blade

May 8, 2012

Confidentiality Label

7

2.4 mm ± 10 %

Layer

Num.Name

Thickness

(mil)

Dielectric

Constant

(Er)

--- 0.7 4.2

1 TOP Plated Copper Foil 1.6

Prepreg 2.8 4.1

2 L2_GND Copper foil 0.6

Core 4 4

3 L3 Copper foil 0.6

Prepreg 10 4.3

4 L4_GND Copper foil 0.6

Core 4 4

5 L5 Copper foil 0.6

Prepreg 10 4.3

6 L6_PWR Copper foil 1.2

Core 4 4

7 L7 Copper foil 1.2

※ Prepreg 10 4.3

8 L8 Copper foil 1.2

Core 4 4

9 L9_PWR/GND Copper foil 1.2

Prepreg 10 4.3

10 L10 Copper foil 0.6

Core 4 4

11 L11_GND Copper foil 0.6

Prepreg 10 4.3

12 L12 Copper foil 0.6

Core 4 4

13 L13_GND Copper foil 0.6

Prepreg 2.8 4.1

14 BOT Plated Copper Foil 1.6

--- 0.7

92.4

93.8 (

2.383 (

Board Thickness (mil)

Total Thickness (mil)

Total Thickness (mm)

SolderMask ---

0.5 oz

1080

0.5oz

Core

0.5oz

Prepreg

0.5oz

Core

0.5oz

Prepreg

1.0oz

Core

1.0oz

Prepreg

1.0oz

Core

1.0oz

Prepreg

0.5oz

Core

0.5oz

Prepreg

0.5oz

Core

0.5oz

1080

0.5 oz

SolderMask ---

PCB Thickness:

Material

RD name: Sam Cheng #1254

Manufacturer: 博智

Model Name: MIC-5332

請板廠依實際

需要微調各疊

層厚度

Page 8: Backplane hsd meeting_may_8th_2012_sharable

STUDYING THE TARGET

IMPEDANCE ROUTING OF THE

BLADE

May 8, 2012

Confidentiality Label

8

Page 9: Backplane hsd meeting_may_8th_2012_sharable

BACKPLANE DESIGN WORKFLOW

STACKUP DEVELOPMENT

May 8, 2012

Confidentiality Label

9

STACKUP

DEVELOPMENT

PCB MATERIAL

PROPERTIES

2D MOM

MET

IMPEDANCE

TARGET?

Page 10: Backplane hsd meeting_may_8th_2012_sharable

Realizing the Stackup in Multi-layer Library in ADS

May 8, 2012

Confidentiality Label

10

Deck: Impedance_compliance_tests-1

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Impedance Analysis

Top Layer Routing on Blade (IC-2-Cap)

4.5/5/4.5 75 Ω (85 Ω – 12%)

08.05.2012 11

Page 12: Backplane hsd meeting_may_8th_2012_sharable

08.05.2012 12

Impedance Analysis

Top Layer Routing on Blade (IC-2-Cap)

3.5/10/3.5 90 Ω (100 Ω – 10%)

08.05.2012 12

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Impedance Analysis

Inner Layer Routing on Blade (Cap-2-ZD Conn)

7/5/7 75 Ω (85 Ω – 12%)

08.05.2012 13

Page 14: Backplane hsd meeting_may_8th_2012_sharable

08.05.2012 14

Impedance Analysis

Inner Layer Routing on Blade (Cap-2-ZD Conn)

5.5/10/5.5 90 Ω (100 Ω – 10%)

08.05.2012 14

Page 15: Backplane hsd meeting_may_8th_2012_sharable

Blade Routing (Top-2-Inner Layer 10)

May 8, 2012

Confidentiality Label

15

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Building blocks of the Blade

Deck: Blade_TOP_2_INNER_FINAL

08.05.2012 16

IC-pad:

21-mils

Mismatch-

TL: 50-mils

Mismatch-

TL: 50-mils

Cap-pads: 28-mils IC-2-Cap-TL:

265-mils

Page 17: Backplane hsd meeting_may_8th_2012_sharable

Building blocks of the Blade

Cap-2-Inner Layer (L10) 3D-Via-Model

08.05.2012 17

TOP-

VIEW

Expanded

Inner-VIEW

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BLADE-VIA Diff-S-CHARACTERISTICS

May 8, 2012

Confidentiality Label

18

Good IL/RL up to 10GHz with

worst IL of ~ -2dB

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TDR Analysis of the Blade-VIA

May 8, 2012

Confidentiality Label

19

The Via drops down the impedance to 82-ohms by 18-ohms

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DEMO FOR THE BLADE-VIA MODELING IN MOM

May 8, 2012

Confidentiality Label

20

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Building blocks of the Blade

Bottom layer or Inner-layer routing

08.05.2012 21

Cap-2-ZD Connector-pad TL

on

Bottom or Inner layers: 1250-

mils

Break-in connector-pad: 975-mils

Mismatch-TL: 50-mils

Page 22: Backplane hsd meeting_may_8th_2012_sharable

Building blocks of the Blade

Bottom-2-Top or

Inner-2-Top ZD Connector PIN-FIELD

08.05.2012 22

BOTTOM-2-TOP VIA FOR

CONNECTOR

INNER-2-TOP VIA FOR

CONNECTOR

Page 23: Backplane hsd meeting_may_8th_2012_sharable

DEMO FOR THE BLADE DECK CONSTRUCTION

May 8, 2012

Confidentiality Label

23

Page 24: Backplane hsd meeting_may_8th_2012_sharable

Agenda

08.05.2012 24

1) Simulation Setup for the Blade

2) I/O driver Setup

3) Blade-2-Blade Investigation

5) Blade-2-Backplane-2-Blade Investigation

6) Backplane Via Structure Sensitivity Analysis and Optimization

7) Conclusion

4) Simulation Setup for the Backplane

Page 25: Backplane hsd meeting_may_8th_2012_sharable

I/O driver Setup

08.05.2012 25

Target Rate is 6.25GB/s

Rise-time=30ps & 20ps

Ron 100-ohms & 90-ohms

De-Emphasis is 5dB with

Tap-interval of 0.4 UI & 0.5 UI

Jitter = 0.01 UI

Test-load

Page 26: Backplane hsd meeting_may_8th_2012_sharable

Reference-eye @ 6.25GB/s

08.05.2012 26

Width = 150ps, height = 1V, Jitter P2P=8ps & Jitter RMS = 1.7ps

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Agenda

08.05.2012 27

1) Simulation Setup for the Blade

2) I/O driver Setup

3) Blade-2-Blade Investigation

5) Blade-2-Backplane-2-Blade Investigation

6) Backplane Via Structure Sensitivity Analysis and Optimization

7) Conclusion

4) Simulation Setup for the Backplane

Page 28: Backplane hsd meeting_may_8th_2012_sharable

Blade-2-Blade without Via Transitions

85W

08.05.2012 28

2.5” 2.5”

Blade-2-Blade without # 3 & 9

without connector &

without Backplane

Page 29: Backplane hsd meeting_may_8th_2012_sharable

Simulation Results

Blade-2-Blade @ 6.25Gb/s (inner 85 Ω-12%) no Vias

De-Emphasis Tap-Interval = 0.5 UI, Ron=100-ohms

08.05.2012 29

Width = 132ps, height = 521mV, Jitter P2P=27ps & Jitter RMS = 5.3ps

Width = 150ps, height = 1V,

Jitter P2P=8ps & Jitter RMS = 1.6ps

4.5

/5 T

OP

& 7

/5 I

NN

ER

Page 30: Backplane hsd meeting_may_8th_2012_sharable

Blade-2-Blade with Via Transitions

85W

08.05.2012 30

2.5” 2.5”

Blade-2-Blade with # 3 & 9

without connector &

without Backplane

Page 31: Backplane hsd meeting_may_8th_2012_sharable

Simulation Results

Blade-2-Blade @ 6.25GB/s (inner 85 Ω-12%) WITH Vias

De-Emphasis Tap-Interval = 0.5 UI, Ron=100-ohms

08.05.2012 31

Width = 100ps, height = 280mV, Jitter P2P=56ps & Jitter RMS = 11.7ps

Width = 150ps, height = 1V,

Jitter P2P=8ps & Jitter RMS = 1.6ps

4.5

/5 T

OP

& 7

/5 I

NN

ER

Page 32: Backplane hsd meeting_may_8th_2012_sharable

Impact of Blade-Vias

08.05.2012

EKH - EyeKnowHow

32

VIAs: Width = 100ps, height = 282mV, Jitter P2P=56ps & Jitter RMS = 11.7ps

NO-VIAS: Width = 132ps, height = 521mV, Jitter P2P=27ps & Jitter RMS = 5.3ps

VIAS IMPACT

Page 33: Backplane hsd meeting_may_8th_2012_sharable

Blade-2-Blade without Via Transitions

100W

08.05.2012 33

2.5” 2.5”

Blade-2-Blade without # 3 & 9

without connector &

without Backplane

Page 34: Backplane hsd meeting_may_8th_2012_sharable

Simulation Results

Blade-2-Blade @ 6.25Gb/s (inner 100 Ω-10%)

De-Emphasis Tap-Interval = 0.5 UI, Ron=100-ohms

08.05.2012 34

Width = 135ps, height = 740mV, Jitter P2P=25ps & Jitter RMS = 5ps

Width = 150ps, height = 1V,

Jitter P2P=8ps & Jitter RMS = 1.6ps

3.5

/10 T

OP

& 5

.5/1

0 I

NN

ER

Page 35: Backplane hsd meeting_may_8th_2012_sharable

Compare (85Ω-12%) to (100Ω-10%)

WITHOUT THE BLADE VIAS

08.05.2012 35

521mV to 740mV

132ps to 135ps

27ps to 25ps

85W TO 100W

Page 36: Backplane hsd meeting_may_8th_2012_sharable

Blade-2-Blade with Via Transitions

100W

08.05.2012 36

2.5” 2.5”

Blade-2-Blade with # 3 & 9

without connector &

without Backplane

Page 37: Backplane hsd meeting_may_8th_2012_sharable

Simulation Results

Blade-2-Blade @ 6.25GB/s (inner 100 Ω-10%)

De-Emphasis Tap-Interval = 0.5 UI, Ron=100-ohms

08.05.2012 37

Width = 125ps, height = 516mV, Jitter P2P=32ps & Jitter RMS = 6.4ps

Width = 150ps, height = 1V,

Jitter P2P=8ps & Jitter RMS = 1.6ps

3.5

/10 T

OP

& 5

.5/1

0 I

NN

ER

Page 38: Backplane hsd meeting_may_8th_2012_sharable

Compare (85Ω-12%) to (100Ω-10%)

WITH THE BLADE VIAS

08.05.2012 38

Eye-heigth:280mV to 516mV

Eye-width: 100ps to 125ps

Jitter-PP: 56ps to 32ps

85W TO 100W

Page 39: Backplane hsd meeting_may_8th_2012_sharable

Recommendations for Blade Routing

Target impedance of 100-ohms is better than 85-ohms:

• Width increase by ~ 25ps

• Height increase by 240mV

• Jitter PP reduces by ~ 25ps

Via Transition Modeling is VERY CRITICAL

08.05.2012 39

Page 40: Backplane hsd meeting_may_8th_2012_sharable

Recommendations for Blade Routing, Contd.

Via Structure should be optimized

• To target impedance (minimum impedance drop for TDR analysis)

• And include Backdrillling

AC Coupling caps should be optimized (e. g. cutout underneath

for better impedance matching)

Avoid routing near cutouts at connector pin field region

08.05.2012 40

Page 41: Backplane hsd meeting_may_8th_2012_sharable

Agenda

08.05.2012 41

1) Simulation Setup for the Blade

2) I/O driver Setup

3) Blade-2-Blade Investigation

5) Blade-2-Backplane-2-Blade Investigation

6) Backplane Via Structure Sensitivity Analysis and Optimization

7) Conclusion

4) Simulation Setup for the Backplane

Page 42: Backplane hsd meeting_may_8th_2012_sharable

Backplane Routing

Longest Stub: Layer-3 w

Length=9685-mils

08.05.2012 42

Page 43: Backplane hsd meeting_may_8th_2012_sharable

Backplane Routing

3D Via modeling

08.05.2012 43

Page 44: Backplane hsd meeting_may_8th_2012_sharable

Backplane Routing

layer 3 routing

08.05.2012 44

Page 45: Backplane hsd meeting_may_8th_2012_sharable

Stackup of the Backplane with Material Properties

45

Core & Pre-preg are 8-mils

Dk = 3.8 @ 10GHz

Loss-Tan = 0.008 @ 10GHz

Page 46: Backplane hsd meeting_may_8th_2012_sharable

OPTIMIZATION OF THE VIA-BP

08.05.2012

46

Page 47: Backplane hsd meeting_may_8th_2012_sharable

Signal-Launch 6-mils away from the ref-GND plane

08.05.2012 47

Signal-Launch 6-mils

away from ref-GND

plane on Bottom

Page 48: Backplane hsd meeting_may_8th_2012_sharable

Via-BP structure without the Extra GND plane at

20-mils from top layer

08.05.2012 48

Page 49: Backplane hsd meeting_may_8th_2012_sharable

Diff IL response of the Via-BP without the extra

GND plane

08.05.2012

49

-9dB @ 10GHz

Page 50: Backplane hsd meeting_may_8th_2012_sharable

Adding Supplement-GND plane is also critical to

keep Diff-IL down @ 10GHz

08.05.2012 50

Adding Suppl-GND plane

helps @ 10GHz

Page 51: Backplane hsd meeting_may_8th_2012_sharable

Via-BP structure with the

Supplement-GND planes

08.05.2012 51

Page 52: Backplane hsd meeting_may_8th_2012_sharable

Diff IL response of the Via-BP with the Supplement

GND plane

08.05.2012

52

-5.5dB @ 10GHz

Page 53: Backplane hsd meeting_may_8th_2012_sharable

CURRENT DENSITY OF THE BP-VIA MOM MODEL

May 8, 2012

Confidentiality Label

53

Page 54: Backplane hsd meeting_may_8th_2012_sharable

BP-CHANNEL PERFORMANCE

08.05.2012

54

Page 55: Backplane hsd meeting_may_8th_2012_sharable

Coupled Simulations of the BP channel

08.05.2012

55

Page 56: Backplane hsd meeting_may_8th_2012_sharable

BP-channel Perf Diff-IL

WITHOUT SUPL-GND Plane

08.05.2012

56

-26dB @ 10GHz

Page 57: Backplane hsd meeting_may_8th_2012_sharable

BP-channel Perf Diff-IL

WITH SUPL-GND Plane

08.05.2012

57

-20dB @ 10GHz

Page 58: Backplane hsd meeting_may_8th_2012_sharable

Do we still have 5/7/5 optimum routing

of BP-channel with Via-BP with

Supplement-GND plane?

08.05.2012

58

Sweeping width from 3.5-mils to 5.5-mils

Sweeping Spacing from 5-mils to 11-mils

Page 59: Backplane hsd meeting_may_8th_2012_sharable

DEMO BACKPLANE CHANNEL CONSTRUCTION

Deck: BP_Channel

May 8, 2012

Confidentiality Label

59

Page 60: Backplane hsd meeting_may_8th_2012_sharable

Conclusion

5/7/5 routing is the optimum routing (sweeping over HVM)

Shifting the Stackup so that the signal-launch is 6-mils away

from the Bottom Ref-GND plane is critical to control the

impedance of the launch

Adding Supplement-GND plane away from the signal-Launch

by 10-mils improve the Via-BP by ~ 4dB and the whole BP-

channel by 6dB @ 10GHz.

08.05.2012 60

Page 61: Backplane hsd meeting_may_8th_2012_sharable

Agenda

08.05.2012 61

1) Simulation Setup for the Blade

2) I/O driver Setup

3) Blade-2-Blade Investigation

5) Blade-2-Backplane-2-Blade Investigation

6) Backplane Via Structure Sensitivity Analysis and Optimization

7) Conclusion

4) Simulation Setup for the Backplane

Page 62: Backplane hsd meeting_may_8th_2012_sharable

Design Focus

• 3D Analysis of the Via-BP as Most-critical Element (minimized

impedance drop to 20-ohms)

• IL & RL Comparison of new-BP Design Compared to

measurements for old-BP

• TDR Analysis of the BP with Connector

• IEEE 802.3ba 2010 Compliance tests of the new BP

• Tx/Rx Equalization Optimization for successful operation at

6.25GBps & 10GBps

• Final Conclusion

62

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Material Properties for FR408HR

08.05.2012

EKH - EyeKnowHow

63

Page 64: Backplane hsd meeting_may_8th_2012_sharable

New Stackup with New Material

64

Core & Pre-preg are 6-mils

Dk = 3.65 @ 10GHz

Loss-Tan = 0.0095 @ 10GHz

Page 65: Backplane hsd meeting_may_8th_2012_sharable

Impedance Compliance for the BP

5/7/5 routing (95-ohms Diff & 54 SE)

65

Disclaimer: recommend that PCB house build a test-coupon & TDR/TDT the

impedance of the test-sample along with S-parameter Data

Page 66: Backplane hsd meeting_may_8th_2012_sharable

How close MOM Estimate to Polar Estimate for

Impedance Calculation?

May 8, 2012

Confidentiality Label

66

54.6 MOM vs. 52.3 Polar 97.6 MOM vs. 95.5 Polar

2-ohms difference in Estimate

Page 67: Backplane hsd meeting_may_8th_2012_sharable

VIA-BP DOMINATES THE

PERFORMANCE OF THE BP

67

Page 68: Backplane hsd meeting_may_8th_2012_sharable

Via-BP structure with the

Supplement-GND planes with FR408HR

68

Page 69: Backplane hsd meeting_may_8th_2012_sharable

Diff IL for the Via-BP up to 15GHz

69

Dip at ‘m2’ 14GHz

Page 70: Backplane hsd meeting_may_8th_2012_sharable

Diff RL for the Via-BP up to 15GHz

70

10GHz < Max reflection < 15GHz

Page 71: Backplane hsd meeting_may_8th_2012_sharable

What is the drop-down-Diff-impedance of the Via-

BP?

71

The via-BP drops the impedance down to 80-ohms

Approximately, it drops the impedance by 20-ohms

Page 72: Backplane hsd meeting_may_8th_2012_sharable

BP-Channel Response w/o CONN:

Longest Channel+ longest Stub

Diff IL with 5/7/5 routing

72

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Comparison with measurements

“L13/14/15/16” compared to Simulated IL

(without the connector)

73

New BP design

without connector

measurements

Page 74: Backplane hsd meeting_may_8th_2012_sharable

Comparison with measurements

“L13/14/15/16” compared to Simulated IL

(with the connector)

74

+6dB Improvement at 10GHz for the new BP Design

compared to measurements

Th

e s

imu

late

d im

pro

ve

me

nt d

ep

en

ds o

n th

e M

od

el q

ua

lity u

se

d.

Be

tte

r co

rre

latio

n to

Me

asu

rem

en

ts is o

bta

ine

d w

ith

Po

st-

layo

ut

Sim

ula

tio

ns

Page 75: Backplane hsd meeting_may_8th_2012_sharable

TDR Analysis BP+Connector

75

Connector H/G-pins

~ 400ps delay

Via-BP

Down by 25-ohms

Page 76: Backplane hsd meeting_may_8th_2012_sharable

Measured TDR of the 6-slots BP

08.05.2012

EKH - EyeKnowHow

76

Almost 70-Ohms dip for

Megatron-6

Page 77: Backplane hsd meeting_may_8th_2012_sharable

COMPLIANCE TESTS OF BP

IEEE STANDARD 802.3BA 2010

77

Page 78: Backplane hsd meeting_may_8th_2012_sharable

Insertion Loss (dB)

78

2 4 6 8 10 12 14 16 180 20

-140

-120

-100

-80

-60

-40

-20

-160

0

freq, GHz

-IL

-IL_m

ax_lo

wer

-IL_m

ax_upper

Page 79: Backplane hsd meeting_may_8th_2012_sharable

Measured IL

79

New-BP is better than old-

BP by +6dB @ 10GHz

Page 80: Backplane hsd meeting_may_8th_2012_sharable

Fitted Attenuation (dB)

80

2 4 6 8 10 12 14 16 180 20

-70

-60

-50

-40

-30

-20

-10

-80

0

freq, GHz

-A-A

_m

ax

-IL

-9dB @ 6GHz

Page 81: Backplane hsd meeting_may_8th_2012_sharable

Measured Fitted Attenuation

08.05.2012

EKH - EyeKnowHow

81

New-BP is better

than old-BP by

+6dB @ 6GHz

Page 82: Backplane hsd meeting_may_8th_2012_sharable

Measured Fitted Attenuation, Contd.

08.05.2012

EKH - EyeKnowHow

82

New-BP is better

than old-BP by

+6dB @ 6GHz

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Insertion Loss Deviation

83

1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.51.0 6.0

-3

-2

-1

0

1

2

3

-4

4

freq, GHz

ILD

ILD

min

ILD

max

Page 84: Backplane hsd meeting_may_8th_2012_sharable

Measured ILD

84

Much better performance of the

new-BP for ILD

Page 85: Backplane hsd meeting_may_8th_2012_sharable

Return Loss (Magnitude)

85

1E91E8 1E10

5

10

15

20

25

30

35

40

45

50

55

0

60

freq, Hz

RL

freq[idx_lower::idx_middle], Hz

RLm

in_lo

wer

RLm

in_m

iddle

freq[idx_upper::idx_fmax], Hz

RLm

in_upper

10GBASE-KR Return Loss Plots with Limit Lines

Page 86: Backplane hsd meeting_may_8th_2012_sharable

BACKPLANE DESIGN WORKFLOW

Meeting the IEEE 802.3ba Target

May 8, 2012

Confidentiality Label

86

VIA PARAMETERS

PCB MATERIAL

PROPERTIES

& STACKUP

3D MOM

MET BP

COMPLIANCE?

BP TL ROUTING

2D MOM

MULTI-LAYER

LIBRARY

Page 87: Backplane hsd meeting_may_8th_2012_sharable

EYE-DIAGRAM CHANNEL

RESPONSE BLADE-BP-BLADE

BLADE IS WORST-CASE 85-W

87

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Eye-Diagram @ 5GBps

Blade-BP-Blade

without Tx/Rx Equalization

88

Blade routing is worst-case of 85-W

Page 89: Backplane hsd meeting_may_8th_2012_sharable

Eye-Diagram @ 5GBps

Blade-BP-Blade

with Rx Equalization (FFE 2/4)

89

Page 90: Backplane hsd meeting_may_8th_2012_sharable

Eye-Diagram @ 6.25GBps

Blade-BP-Blade

with Rx Equalization (DFE 6-taps )

90

Page 91: Backplane hsd meeting_may_8th_2012_sharable

OPTIMIZATION OF DRIVER FIR

EQUALIZER SETTING AND

RECEIVER DFE SETTINGS @

6.25GBPS

91

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Jitter PP Optimized setting:

Tx FIR pre-cursor = ‘3’, post=‘5’

92

Worst jitter

pp=30ps

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Eye-width

93

Worst eye-

width = 130ps

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Eye-height

94

Worst height

= 1.58V

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eye-diagram with all FIR EQ settings

95

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OPTIMIZATION OF TX FIR

EQUALIZATION SETTINGS FOR

10GBPS OPERATION

96

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Jitter PP Min

FIR Setting: pre-cursor ‘1’ post ‘5’

97 Jitter 38ps

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Eye-width maximization

98 Width is 62ps

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Eye-height max

99 Height is 240mV

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eye-diagram combined

100

Best FIR setting is

Pre-cursor ‘1’ & post ‘5’

Page 101: Backplane hsd meeting_may_8th_2012_sharable

DEMO SETTING THE TX FIR EQUALIZATION

PARAMETERS

May 8, 2012

Confidentiality Label

101

Page 102: Backplane hsd meeting_may_8th_2012_sharable

Conclusion

• Via-BP was shown to dominate the performance of the BP especially > 5GBps (new-Via-BP causes ONLY 20-ohms to 25-ohms drop in impedance with TDR analysis)

• New Material + stackup + via-BP +6dB improvement in IL @ 10GHz for worst-BP-channel (longest with longest stub) passes all Compliance tests IEEE 802.3ba 2010

• Tx FIR & Rx DFE Equalization helps open the eye for higher data rates of 6.25GBps and above

• successful FIR settings of Tx & DFE settings of Rx was shown @ 6.25GBps & 10GBps

102

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IBIS-AMI MODELING DISCUSSION

May 8, 2012

Confidentiality Label

103

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In Statistical Channel simulation mode, can we use

RX adaptive DFE in simulation and output DFE

taps?

For example, Broadcomm warplite_kr rx AMI

model, there is no Getwave function, but it include

DFE and there is no problem to run DFE channel

simulation. Altera S4/S5 AMI model, under

Statistical channel simulation, it is also OK to

include DFE model.

May 8, 2012

Confidentiality Label

104

Page 105: Backplane hsd meeting_may_8th_2012_sharable

105

Two Kinds of Tx/Rx Plus

a “Hybrid”

Model’s Init_Returns_Impulse flag

is:

False (“Can’t be

modeled as LTI”)

True (“LTI model

via impulse

response”)

Model’s

GetWave_Exists

flag is:

False (“Model is

pure LTI”)

Empty model: not

allowed

Typical case for

Tx and simple

Rx’s (fixed Eq.

and no CDR)

True (“NLTV

model via

waveform

modification”)

Typical case for

Rx (Adaptive Eq.,

CDR)

Buyer beware:

LTI approximation

of NLTV device if

used in stat mode

Page 106: Backplane hsd meeting_may_8th_2012_sharable

Channel Simulator:

Statistical Mode

Tx model’s Init_Returns_Impulse

flag is:

False (“Tx

cannot be

modeled as

LTI”)

True (“Tx can be

modeled as LTI

using

AMI_Init()”)

Rx model’s

Init_Returns_Impulse

flag is:

False (“Rx

cannot be

modeled as LTI”)

True (“Rx can be

modeled as LTI

using AMI_Init()”)

“Case 1”

106

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107

Channel Simulator:

Bit-by-bit mode

Tx model’s GetWave_Exists flag is:

False (“Tx has

no NLTV

character”)

True (“Tx

models NLTV by

modifying

waveform”)

Rx model’s

GetWave_Exists

flag is:

False (“Rx has

no NLTV

character”)

“Case 2” “Case 5”

(Practically never

used)

True (“Rx

models NLTV by

modifying

waveform”)

“Case 3” (Most

common case)

“Case 4”

Page 108: Backplane hsd meeting_may_8th_2012_sharable

Five Cases

108

Mode Bit pattern? Tx Analog &

Channel

Rx

1 Statistical None: stochastic

properties of

infinite bit pattern

LTI LTI LTI

2 Bit-by-bit Any finite bit

pattern

LTI LTI* LTI

3 Bit-by-bit Any finite bit

pattern

LTI LTI* NLTV

4 Bit-by-bit Any finite bit

pattern

NLTV LTI* NLTV

5 Bit-by-bit Any finite bit

pattern

NLTV LTI LTI

*ADS can handle NLTV mid-channel repeaters

using a proprietary extension

Page 109: Backplane hsd meeting_may_8th_2012_sharable

1. Analog and

channel impulse

response

2. “Smart” convolve

with Tx

3. “Smart” convolve

with Rx

Pre-Work for Thru Channel: All 5 Cases

109

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Case 1: Statistical Mode

Tx and Rx modeled by their impulse responses

Eye pattern diagram (density, BER contours, bathtubs)

calculated directly from pre-work:

…using statistical methods that include jitter and crosstalk

handling

110

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Case 3: Bit-by-bit Mode: Tx modeled by impulse

response, Rx modeled by waveform modification

1. Bit pattern:

2. Convolve with composite analog/channel/Tx impulse:

3. Modify waveform using Rx model algorithm:

4. Eye pattern diagram from Rx output waveform

• Details of jitter handling in next slide…

111

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Two Methods of Handling Rx Jitter

112

1) When clock ticks are available:

bit-by-bit and clock ticks available from Rx

GetWave

…waveform segments between [tick, tick+UI]

are used to construct the eye to capture Rx

sample time jitter. Eye is centered at tick+UI/2.

2) When clock ticks are not available, Rx_Clock_PDF is convolved with

eye pattern diagram:

• Statistical mode

• Bit-by-bit mode but no clock ticks

UI

UI

UI

tick 1

tick 2

tick 3 eye center @ tick+UI/2