© Verigy Ltd. 2010

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SSC AppliedHigh-speed Serial Interface

Signal Generation and Analysis by Analog Resources

Hideo Okawara

Verigy Japan K.K.

© Verigy Ltd. 2010

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Purpose

• High-speed Serial Interface

– SSC Applied Signal Waveform

• Application of Analog Resources

– Generation by a UHF AWG

– Analysis by a Waveform Sampler

© Verigy Ltd. 2010

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Outline

• Introduction• Signal Generation

• Signal Analysis– SSC Applied Clock

– SSC Applied Align Primitive

• Conclusion

© Verigy Ltd. 2010

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Fc

Magn

itude

Frequency

SSC AppliedClock

PeakReduced

Fc

Magn

itude

Frequency

OriginalFixed Clock

“SSC”Spread Spectrum Clocking

© Verigy Ltd. 2010

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1.5Gbps SATA SSC Spec.

1,500.0

1,492.5

Bit R

ate

[M

bps]

0.5% Down Spread

30us.. 33us (30kHz..33kHz)

666.7

670.0

Un

it I

nte

rval [ps]

7.5

MH

z

3.3

5p

s

© Verigy Ltd. 2010

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Data Structure

Align Primitive (40 bits)

0011111010010101010101010101010010011100

10-bit Word 8b10b Conversion

4 Words

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Increasing/Decreasing Period

~30us

=4,536x10=1,134x40

3.35ps

~15us

~15us

#1

Min. 667ps#0 0.148fs

45,360 bitsMax. 670ps

Min. 667ps

#22,678

#22,681

#45,359

#45,358

#22,679

#22,680

© Verigy Ltd. 2010

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Elastic UI � Amplitude

Sampling Timing

0.148fs

Square Shape

Exponential Curve

© Verigy Ltd. 2010

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Outline

• Introduction

• Signal Generation• Signal Analysis

– SSC Applied Clock

– SSC Applied Align Primitive

• Conclusion

© Verigy Ltd. 2010

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Signal Programming Steps

Total 45,360 bits (@ 1.5Gbps)

1,048,576=220 points (@ 34.6Gsps)

Digital Data

Rolled-offWaveform

124,288 points (@ 4.1Gsps)AWG Waveform

Re-sampling

1 SSC Cycle (30 usec)

1,048,576=220 points (@ 34.6Gsps)Filtered

Waveform

Filtering

Conversion

© Verigy Ltd. 2010

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Initial Rolled-off Waveform Exponential Curve

@ 34.6Gsps

Data 0

(1 to 0 Transition)

Data 1

(0 to 1 Transition)

1 UI

Am

plit

ud

e

Time~23 points

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Extract Main Lobe by Filtering

Initial Spectrum

Band-limited Spectrum

1.5GHz

Magn

itude [

dB

]

-20

-60

-40

-60

-40

-80

1.5 3 60 9 12 15

Frequency [GHz]

© Verigy Ltd. 2010

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Re-sampling

Initial

@ 34.6Gsps

1,048,576 points

1000 1200

(a)

Main Lobe

@ 34.6Gsps

1,048,576 points

1000 1200

Am

plit

ud

e

(b)

Re-sampled@ 4.1Gsps124,288 points

100 140120Address

(c)

© Verigy Ltd. 2010

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Typical Test Signal Data

750MHz Clock

375MHz Clock

Align Primitive

PRBS Words

01

0011

© Verigy Ltd. 2010

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Generated Signal Spectrum

750MHz

3.75MHz

1GHz

1GHz

Clock Align Primitive

PRBS WordSpectrum Analyzer:

Agilent E4440A

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Generated Signal WaveformDigital Signal Oscilloscope: Agilent Infiniium DSA91304A 13GHz

© Verigy Ltd. 2010

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Generated Signal WaveformDigital Signal Oscilloscope: Agilent Infiniium DSA91304A 13GHz

© Verigy Ltd. 2010

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Outline

• Introduction

• Signal Generation

• Signal Analysis

– SSC Applied Clock– SSC Applied Align Primitive

• Conclusion

© Verigy Ltd. 2010

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UHF

AWG

4.1Gsps

Waveform

Sampler

Fs=25.62345…Msps

N=16,384 points

750MHz Clock

with 33kHz SSC

124,288 points

Experimental Configuration (A)

© Verigy Ltd. 2010

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Spectrum in Under-sampling

Baseband

Front Page Back Page Front Page Front Page Front PageBack Page Back Page

N 2N 3NN/2Frequency Bin #

Baseband Baseband

Spectrum DisplayFolding all pages.

M

Frequency Domain

0 N/20 N/2

0

FsFs/2

0 N/2

Baseband

© Verigy Ltd. 2010

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-20

-80

-40

-60

Magnitu

de [

dB

]

0 5 10(Baseband) Frequency [MHz]

Time [us]0 200 400 600

1.0

-1.0

0.0

Am

plit

ud

e [

V]

4

Fs=25.62345…MspsN=16,384 points

Waveform750MHz Clock

Spectrum

321 6 7 8 9 11 12

3.75MHz

Waveform and Spectrum

© Verigy Ltd. 2010

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Orthogonal Demodulation

DUT

LPF

Fref tan-1( )Im

Re

dΦ

dt

Re

Im

+π

-π

f(t)

LPF

Post Processing in the Computer

Φ(t)Sampler

cos

sin

© Verigy Ltd. 2010

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ODM by Equations

Reference Multiplication:

Low Pass Filtering:

Arctangent:

Differentiation:

g(t)=Acos(ωt+θ)

arctany(t)x(t)

= (ω-ωr)t+θ = Φ(t)

dΦ

dt= ω-ωr

g(t)▪cos(ωrt) = {cos((ω-ωr)t+θ)+sin((ω+ωr)t+θ)}

g(t)▪(-sin(ωrt))= {sin((ω-ωr)t+θ)-cos((ω+ωr)t+θ)}

A2

A2

x(t)= cos((ω-ωr)t+θ)

y(t)= sin((ω-ωr)t+θ)

A2A2

Test Signal Waveform:

© Verigy Ltd. 2010

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Reference Multiplication

-30

-50

-70Ma

gn

itud

e [dB

]

Reference (748.12MHz)

Ma

gn

itud

e [dB

]

-50

-70 Beat Sum

-30

50 10Frequency [MHz]

31 2 4 6 7 8 9 11 12

Initial Spectrum

© Verigy Ltd. 2010

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Reference Multiplication

-30

-50

-70Ma

gn

itud

e [dB

]

Reference (748.12MHz)

Ma

gn

itud

e [dB

]

-50

-70 Beat Sum

-30

50 10Frequency [MHz]

31 2 4

Low Pass Filter

6 7 8 9 11 12

Initial Spectrum

© Verigy Ltd. 2010

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Instantaneous Phase

arctanBeat(sin)

Beat(cos)ω ωr t + θ

0 200 400 600

Time [us]

0

-30

-60

-90

Phase [

rad]

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0 200 400 600Time [us]

750

746

748

30us

3.75MHz

Fre

que

ncy [

MH

z]

SSC Frequency Trend

ω ωr t + θd

dtω ωr

© Verigy Ltd. 2010

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Spectrum of SSC Trend

-90

0

-30

-60Ma

gn

itud

e [dB

]

0.4 0.60Frequency [MHz]

Fundamental(33kHz)

1.40.2 1.20.8 1.0

© Verigy Ltd. 2010

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Ideal Triangle Subtraction F

requ

ency [M

Hz]

2.0

-2.0

0.0 Reconstructed SSC Trend

0 200 400 600Time [us]

0.0

0.1

-0.1

Residual Noise Waveform

A ▪ {cos(ωt )+19

cos(3ωt )+ 125

cos(5ωt )+ … }

Ideal Triangle Waveform

© Verigy Ltd. 2010

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Original Spectrum

-90

0

-30

-60Magn

itude [

dB

]

0.4 0.60Frequency [MHz]

1.40.2 1.20.8 1.0

© Verigy Ltd. 2010

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Residual Noise Spectrum

-90

0

-30

-60Magn

itude [

dB

]

0.4 0.60Frequency [MHz]

1.40.2 1.20.8 1.0

© Verigy Ltd. 2010

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Outline

• Introduction

• Signal Generation

• Signal Analysis

– SSC Applied Clock

– SSC Applied Align Primitive

• Conclusion

© Verigy Ltd. 2010

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UHF

AWG

4.1Gsps

Waveform

Sampler

Fs=99.04Msps

N=16384 points

Align Primitive

with 33kHz SSC

124288 points

Experimental Configuration (B)

© Verigy Ltd. 2010

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Spectrum of Align Primitive1GHz 2

123…

1 2 3 393837

7.5MHz x = ~7.5MHz 39

407.5MHz x = ~0.19MHz

1

40

0

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Signal in Under-sampling

Folding

N 2N 3NN/2

Frequency Domain

0

Fs

N/20 N/20 0 N/2

Entire SpectraOverlap

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-20

-30

-40

-50

-60

-700 20 30 40 5010

Frequency [MHz]

Magn

itude [

dB

]Spectrum of Align Primitive

© Verigy Ltd. 2010

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Frequency TrendF

reque

ncy [

MH

z]

30us

37.5

74.8

112.2

149.6

187.1

224.5

299.2

0.19MHz

0.38MHz

0.56MHz

0.75MHz

0.94MHz

1.1MHz

1.5MHz

© Verigy Ltd. 2010

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Outline

• Introduction

• Signal Generation

• Signal Analysis

– SSC Applied Clock

– SSC Applied Align Primitive

• Conclusion

© Verigy Ltd. 2010

39

Conclusion

• UHF AWG generates SSC applied signal.

– SSC Applied Clock

– SSC Applied Align Primitive

– SSC Applied PRBS Encoded Words

• Waveform Sampler analyzes limited SSC applied signal.

– SSC Applied Clock: Spectrum & SSC Trend

– SSC Applied Align Primitive: SSC Trend

© Verigy Ltd. 2010

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Thank you for your attention.