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ni.com
Overcome High-Speed Analog
Measurement ChallengesPresenter
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Agenda
High-Speed Test Challenges
Oscilloscope/Digitizer Performance Requirements
Automated Test Challenges Addressing Automated Test Challenges With the
Industrys Highest Performance PXI Digitizers
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High-Speed Test Challenges
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There are two kinds of designers . . .
those that have signal integrity problems
. . . and those that will.
Sun Microsystems
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High-Speed Test Challenges
Source: EE Times survey
Signal integrity is criticalCircuit board traces become transmission lines
Impedance discontinuities along the signal path:
Create reflections Degrade signal edges
Increase crosstalk
EMI goes up Ground bounce increases with highercurrent
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What Is Signal Integrity?
A digital signal with good integrity has: Clean, fast transitions Stable, valid logic levels
Accurate placement in time
Free of transients
The term integrity means complete and unimpaired.
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Measuring Signal Integrity
Visual tool to observe signalintegrity on a clocked bus, usuallymeasured using anoscilloscope/digitizer
Overlays waveform traces frommany successive unit intervals
Signal integrity factors causeblur:
Jitter (horizontal) Noise (vertical)
Eye Diagram
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Oscilloscopes/Digitizers Provide Insight
Into the Analog Domain
Displays waveform details,edges, and noise
Detects and displays transients
Precisely measures timingrelationships
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Oscilloscope/Digitizer
Performance Requirements
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Signal Integrity Versus Signal Fidelity
Signal integrity: Is my circuit operating as expected?
Signal fidelity: Can I trust my measurement system to
give an accurate representation of my signal?
How do you know if your measurement setupprovides good signal fidelity?
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Measurement Bandwidth
Oscilloscope Bandwidth Must have sufficient
bandwidth to capture high-
frequency components
Bandwidth specified at -3 dBpoint
The 5 Times Rule
For less than2 percent
measurement error
Bandwidth 5thHarmonic>
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Sample Rate
Sample Rate Determines how frequently an
oscilloscope takes a sample
Faster sample rate, greaterresolution and waveform detail
Wider margins in production testmay demand less oversampling
Required Sample RateSample
Rate 2.5 X fHighest>For sin(x)/x interpolation
Sample
Rate 10 X fHighest>For linear interpolation
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Vertical Resolution
Vertical resolutionrefers to how manydifferent voltagechanges you canmeasure
100 200150500
Time (ms)
0
1.25
5.00
2.50
3.75
6.25
7.50
8.75
10.00
Amplitude (V)
16-bit resolution
3-bit resolution
000
001
010
011
100
101
110
111
| ||||
However
vertical resolution alone doesnt tell the whole story!
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Characterizing Acquisition Performance
Sources of rrorDifferential Nonlinearity
Integral NonlinearityMissing Codes
Aperture Uncertainty
Noise
How do we characterizethe impact of theseerror sources?
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Effective Number of Bits (ENOB)
Characterizes how closely a digitized waveform actuallyrepresents the analog input signal
Higher effectivenumber of bitsprovides better
voltageresolution
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ENOB: Figure of Merit for High-Speed Digitizers
Why use ENOB?
Accounts for all of the following error sources:
Differential nonlinearity
Integral nonlinearity
Missing codesAperture uncertainty
Noise
Indicates the impact of noise and distortion sources
across signal frequencies
ENOB typically degrades with increasing signal
frequency
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Value of Looking Into ENOB
NI PXIe-5185/86 Digitizer A Digitizer B
Analog Bandwidth 3 GHz and 5 GHz 3 GHz 1.5 GHz
Sample Rate 12.5 GS/s 8 GS/s 4 GS/s
Vertical Resolution 8-bit ADC 10-bit ADC 10-bit ADC
Which would you expect to provide better vertical resolution?
Sampling Jitter 500 fs RMS 1200 fs RMS 1200 fs RMS
RMS Noise 0.35% full scale Not specified 0.5% full scale
ENOB6 bits at 2.5 GHz
5.5 bits at 5 GHz
4.5 bits at 1.8
GHz
Not specified
above 410 MHz
Form Factor 3U PXI Express 6U CompactPCI 3U PXI
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ENOB for High Speed Measurements
Input the same 5 Gbit/s signalto both instruments
High ENOB translates intomore margin and better
repeatability!
Measurement Vendor T Vendor A
TIE Jitter 3.08 ps 11.4 ps
Eye Height 582 mV 521 mV
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Automated Test Challenges
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A digitizer providesfeatures optimized forautomated test
Test Throughout the Development Cycle
Production
TestValidationR&D
OscilloscopesQuick Visualization
Interactive Use
High Bandwidth
Modular DigitizersHigh Throughput
Integration
Compact Size
Very High Bandwidth (multi-GHz)
Customized measurements
Hybrid
Systems
The digitizing oscilloscopeprovides insight into theanalog domain
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Automated Test Challenges
System IntegrationCombining driver software from multiple
vendorsSharing of clocks and triggersFuture-proofing for upgraded capabilitySynchronizing channels in large systems
Reduced Test Times Peripheral buses not optimized for throughput
or latency
Limited Rack Space Stand-alone oscilloscopes can consume 7U to 8U
of rack space
Power Constraints
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Addressing Automated Test Challenges With the
Industrys Highest Performance PXI Digitizers
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Industrys Highest Performance PXI Digitizers
NI PXIe-5185 NI PXIe-5186Bandwidth 3 GHz 5 GHz
Sample Rate12.5 GS/s (1 ch)
6.25 GS/s (2 ch)
Channels 2
Vertical Resolution 8-Bit ADC
Data Throughput >700 MB/s
Form Factor 3-Slot, 3U PXI Express
CodevelopedbyNI and Tektronix
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Superior Acquisition Performance
State-of-the-art SiGe analog-to-digital converters and front-
end ASICs designed by Tektronix, manufactured by IBM
Same core technology is deployed across Tektronix
oscilloscopes offering
Tektronix, Enabling Technology is a trademark of Tektronix, Inc.
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NI PXIe-5185/86: Optimized for Automated Test
Simplified System IntegrationNI-SCOPE driver for all NI digitizersShare triggers using the matched trigger lines of the PXI
backplaneSupport for all popular application development environmentsMultimodule synchronization at 80 ps resolution over PXI
backplane Reduced Test Times
Data throughput rates >700 MB/s
Smallest Footprint Fit 10 channels in a single chassis
Minimal Power Consumption 45 W/ch power consumption (90 W per module)
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Reduce Test Times With PXI Express
Block
Size
NI PXIe-5186/5185
Digitizers
LXI GigabitEthernet
Oscilloscope
Test Time
Reduction
1 MB 496 MB/s 12.6 MB/s 39.4x
16 MB 700 MB/s 19.7 MB/s 35.5x33 MB 738 MB/s 20.3 MB/s 36.4x
Why the difference?
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Rack Space
1,951 in3
Power Consumption: 375 W
104 in3
Power Consumption: 90 W
Digital multimeter, battery simulator,signal generator, spectrum
analyzer, digitizer, switch, digital
I/O, coprocessor, RF transceiver,
embedded PC
4U Rack Height
Power Consumption: 790 W8U Rack Height
Power Consumption: 375 W
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Custom Measurements
NI LabVIEW Toolkits
Processing
Jitter Analysis Signal Processing Digital Filter Design Modulation Spectral Meas.
Upgrade to the latestprocessor technology
using embedded
controllers
Take advantage of
multicore processors
with LabVIEW
Perform inlineprocessing with
NI FlexRIO and
LabVIEW FPGA
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Summary
For high-speed digitizers, ENOB offers the best figure
of merit for comparing noise performance
Tektronix, Enabling Technology in the
NI PXIe-5185/86 delivers superior signal fidelity with
low noise and high ENOB
NI PXIe-5185/86 modules are optimized for automated
test
Tektronix, Enabling Technology is a trademark of Tektronix, Inc.
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For More Information
For NI PXIe-5185/86 product information, visit
ni.com/high-speed-digitizer.
To learn more about PXI and its benefits for
automated test, visit ni.com/automatedtest.
http://www.ni.com/high-speed-digitizerhttp://www.ni.com/automatedtesthttp://www.ni.com/automatedtesthttp://www.ni.com/high-speed-digitizerhttp://www.ni.com/high-speed-digitizerhttp://www.ni.com/high-speed-digitizerhttp://www.ni.com/high-speed-digitizerhttp://www.ni.com/high-speed-digitizer8/13/2019 Overcome High-Speed Analog Measurement Challenges
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