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© Verigy Ltd. 2010
1
SSC AppliedHigh-speed Serial Interface
Signal Generation and Analysis by Analog Resources
Hideo Okawara
Verigy Japan K.K.
© Verigy Ltd. 2010
2
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
3
Outline
• Introduction• Signal Generation
• Signal Analysis– SSC Applied Clock
– SSC Applied Align Primitive
• Conclusion
© Verigy Ltd. 2010
4
Fc
Magn
itude
Frequency
SSC AppliedClock
PeakReduced
Fc
Magn
itude
Frequency
OriginalFixed Clock
“SSC”Spread Spectrum Clocking
© Verigy Ltd. 2010
5
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
6
Data Structure
Align Primitive (40 bits)
0011111010010101010101010101010010011100
10-bit Word 8b10b Conversion
4 Words
© Verigy Ltd. 2010
7
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
8
Elastic UI � Amplitude
Sampling Timing
0.148fs
Square Shape
Exponential Curve
© Verigy Ltd. 2010
9
Outline
• Introduction
• Signal Generation• Signal Analysis
– SSC Applied Clock
– SSC Applied Align Primitive
• Conclusion
© Verigy Ltd. 2010
10
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
11
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
© Verigy Ltd. 2010
12
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
13
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
14
Typical Test Signal Data
750MHz Clock
375MHz Clock
Align Primitive
PRBS Words
01
0011
© Verigy Ltd. 2010
15
Generated Signal Spectrum
750MHz
3.75MHz
1GHz
1GHz
Clock Align Primitive
PRBS WordSpectrum Analyzer:
Agilent E4440A
© Verigy Ltd. 2010
16
Generated Signal WaveformDigital Signal Oscilloscope: Agilent Infiniium DSA91304A 13GHz
© Verigy Ltd. 2010
17
Generated Signal WaveformDigital Signal Oscilloscope: Agilent Infiniium DSA91304A 13GHz
© Verigy Ltd. 2010
18
Outline
• Introduction
• Signal Generation
• Signal Analysis
– SSC Applied Clock– SSC Applied Align Primitive
• Conclusion
© Verigy Ltd. 2010
19
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
20
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
21
-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
22
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
23
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
24
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
25
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
26
Instantaneous Phase
arctanBeat(sin)
Beat(cos)ω ωr t + θ
0 200 400 600
Time [us]
0
-30
-60
-90
Phase [
rad]
© Verigy Ltd. 2010
27
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
28
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
29
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
30
Original Spectrum
-90
0
-30
-60Magn
itude [
dB
]
0.4 0.60Frequency [MHz]
1.40.2 1.20.8 1.0
© Verigy Ltd. 2010
31
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
32
Outline
• Introduction
• Signal Generation
• Signal Analysis
– SSC Applied Clock
– SSC Applied Align Primitive
• Conclusion
© Verigy Ltd. 2010
33
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
34
Spectrum of Align Primitive1GHz 2
123…
1 2 3 393837
7.5MHz x = ~7.5MHz 39
407.5MHz x = ~0.19MHz
1
40
0
© Verigy Ltd. 2010
35
Signal in Under-sampling
Folding
N 2N 3NN/2
Frequency Domain
0
Fs
N/20 N/20 0 N/2
Entire SpectraOverlap
© Verigy Ltd. 2010
36
-20
-30
-40
-50
-60
-700 20 30 40 5010
Frequency [MHz]
Magn
itude [
dB
]Spectrum of Align Primitive
© Verigy Ltd. 2010
37
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
38
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
40
Thank you for your attention.