Keysight N9068A User manual

This demonstration guide will guide you through some
typical usage scenarios for the Keysight Technologies, Inc.
X-Series signal analyzers with the N9068A/W9068A phase
noise measurement application. Each demonstration is given
a brief description of its function and the corresponding
measurement steps on the signal generator and/or signal
analyzer.
Keysight Technologies
N9068A & W9068A Phase Noise
X-Series Measurement Application
Demo Guide

2
Demonstration Preparation
All demonstrations use an X-Series
signal analyzer with the phase noise
measurement application and the
N5181A MXG analog signal generator
(unless otherwise noted). Keystrokes
surrounded by [ ] indicate front-panel
keys; keystrokes surrounded by
{ } indicate softkeys located on the
display.
Minimum equipment conguration requirements
Product type Model number Required options
MXG (or PSG,
ESG) analog or
vector signal
generator
N5181A or any other
signal generator with CW
RF signal output
– Option 503 or any other frequency option
X-Series signal
analyzer
N9030A PXA, N9020A
MXA, N9010A EXA, or
N9000A CXA
– Option 503 or any other frequency option
Phase noise
measurement
application
N9068A (PXA, MXA, EXA)
W9068A (CXA)
– Option 2FP – fixed perpetual license
– Option 2TP – transportable perpetual
license (not available for CXA)
Figure 1. Demonstration setup
Demonstration Setup
Connect the X-Series and MXG
Perform the following steps to
interconnect the X-Series and MXG
(see Figure 1 for a graphical overview):
A. Connect the MXG RF output port
to the X-Series RF input port with
a 50 Ω RF cable
B. Connect the MXG “REF IN” to the
X-Series “10 MHz OUT” port (rear
panel) with a BNC cable
Helpful tip:
Update your instrument firmware and software
to the latest version, available at
www.keysight.com/find/xseries_software
www.keysight.com/find/signalstudio
REF IN
10 MHz
OUT

3
Demonstrations
Demonstration 1:
Getting started
The signal under test is simply a
continuous-wave (CW) RF signal from
the MXG. Recommended settings
for signal generator are 1 GHz center
frequency and –10 dBm RF output
level.
Instructions Keystrokes
On the MXG signal generator
Preset the MXG [Preset]
Set up the signal under test at 1 GHz
center frequency and –10 dBm output
level
[FREQ] [1] {GHz}; [AMPLD] [-] [10] {dBm}
Turn off modulation
[Mod On/Off] and ensure the LED under the key
is off
Turn on RF output
[RF On/Off] and ensure the LED under the key
is lit
On the X-Series signal analyzer
Switch to Phase Noise mode [Mode] {Phase Noise}
Set the signal analyzer with a carrier
frequency of 1 GHz and an amplitude
reference level of 0 dBm
[FREQ Channel] {Carrie Freq} [1]{GHz}; [AMPTD
Y Scale] {Ref Value} [0] {dBm}
View the signal at spectrum domain
using “Monitor Spectrum”. It is
always a good idea to use the moni-
tor spectrum measurement to make
sure your X-Series signal analyzer set
to the right frequency.
[Meas] {Monitor Spectrum}
Figure 2. Monitor spectrum to check the signal coming from the DUT

4
Demonstration 2:
Log plot measurement
The log plot is the most-frequently
used presentation of a DUT’s phase
noise performance. It measures
single-sideband phase noise (in dBc/
Hz) versus offset frequencies from the
carrier on a logarithmic scale.
View the entire phase noise behavior
across decades of offset frequencies.
Adjust the number of decades by
selecting the appropriate start and
stop offsets.
Perform trace smoothing with the
user-adjustable smoothing segment
length and view it superimposed with
the raw data trace.
Figure 3. Log plot phase noise with a smoothed trace and decade table turned on
Instructions Keystrokes
On the X-Series in Phase Noise mode:
View log plot [Meas] {Log Plot}
Set the signal analyzer with a carrier fre-
quency of 1 GHz and an amplitude reference
level of 0 dBm
[FREQ Channel] {Carrie Freq} [1]
{GHz}; [AMPTD Y Scale] {Ref Value}
[0] {dBm}
Set the start offset to 100 Hz and stop
offset to 100 MHz and restart the log plot
measurement
[SPAN X Scale] {Start Offset} [100]
{Hz}; {Stop Offset} [100] {MHz}, then
[Restart]
Turn the Decade table on, so that you can
have both graphic and tabular presentations
[Meas Setup] {More 1 of 2},
{Decade Table on}

5
Demonstration 3:
Integrated noise
measurement
Depending upon applications, other
aspects of the phase noise may better
serve the purpose of evaluating your
DUT’s phase noise behaviors. In the
digital world, root-mean-square (rms)
phase deviation/jitter (in degrees
or radians) and rms phase jitter (in
seconds) are used more frequently
to evaluate the stability of a high-
frequency clock. On the other hand,
residual FM is more important to
amplifier designers and manufacturers.
The X-Series signal analyzers make
these measurements easy with
advanced marker functions applied
on the measurement result of the
Log plot.
Figure 4. Calculate rms jitter and residual FM using band marker functions
Instructions Keystrokes
On the X-Series Phase Noise mode:
View Log plot [Meas] {Log Plot}
Set the signal analyzer with a carrier
frequency of 1 GHz and an amplitude
reference level of 0 dBm
[FREQ Channel] {Carrie Freq} [1] {GHz};
[AMPTD Y Scale] {Ref Value} [0] {dBm}
Set the start offset to 100 Hz and stop
offset to 100 MHz and restart the log plot
measurement
[SPAN X Scale] {Start Offset} [100]{Hz};
{Stop Offset} [100]{MHz}, then [Restart]
Activate markers for the rms jitter
measurements [Marker Function] {RMS Noise} {Jitter}
Set an integrated band and get the
integrated noise measurement results
{Band Adjust} {Band/Interval Left} [1]
{kHz}, {Band/Interval Right} [10] {kHz},
then read the value in bold green font on
the top right corner of the display
Turn on the marker table [Marker] {More 1 of 2} {Marker Table On}
Add the residual FM measurement with a
different integrated band being set
[Maker Function] {Select Marker}
{Marker 2} {Residual FM}; {Band
Adjust} {Band/Interval Left} [50]{kHz},
{Band/Interval Right} [100] {kHz}, then
read the value in bold green font on the
top right corner of the display

6
Demonstration 4:
Spot frequency measurement
Spot frequency measurement inves-
tigates the phase noise behavior at a
specific offset frequency by providing
the time domain view.
With the signal tracking function
on (the defaulted state), the carrier
frequency drift can be observed.
Figure 5. Spot frequency measurement provides carrier frequency drift view and phase noise change
versus time in a specific offset
Instructions Keystrokes
On the X-Series signal analyzer:
Start Spot frequency [Meas] {Power Stat CCDF}
Set the signal analyzer with a carrier
frequency of 1 GHz
[Trace/Detector] {Store Ref Trace}
Set the spot offset frequency to 10 kHz [Trace/Detector] {Ref Trace On}
On the MXG
Set the incremental frequency at 10 Hz
per step
[FREQ] [Incr Set] [10] {kHz}, then [↑]
or [↓] to manually adjust the carrier
frequency drift by 10 kHz/step
On the X-Series Phase Noise mode:
Adjust the signal analyzer’s Y-axis scale
according to the 10 Hz/step set on the MXG.
Manually adjust the RF carrier frequency
from the output of the signal generator up or
down by 10 Hz steps to see the stair shaped
trace in the delta frequency pane.
Press the third button from the power
switch at the analyzer’s front panel to
activate the “Delta Freq” pane (with
a light green frame), then [AMPTD]
{Scale/Div} [10] {Hz}
View the spot frequency phase noise along
with the numerical results of the SSB phase
noise table
[View/Display] {Numerical}
Turn the signal tracking off [FREQ Channel] {Signal Tracking Off}

7
Demonstration 5:
Displayed average noise
level (DANL) measurements
and reference trace
subtractions
The DANL floor of the signal analyzer
may adversely affect the phase noise
measurement results, particularly
at the wider offset. The DANL mea-
surement provided by the N9068A/
W9068A measures and references the
X-Series signal analyzer to the carrier
amplitude.
Furthermore, the measured DANL
can be used as a reference trace
when implementing reference trace
subtraction to eliminate the analyzer’s
broadband noise effect from the
phase noise measurements.
Instructions Keystrokes
On the X-Series Phase Noise mode:
Start DANL measurement and set the
average number to 20. The signal analyzer
averages 20 measurements – wait for
the measurement to finish (the Avg|Hold
counter in the measurement status bar at
the top of the display helps keep track of
the status).
[Mode preset] [Meas] {Log Plot} [Meas
Setup] {Avg Number On} [20] {Enter}, {Meas
Type} {DANL} [Restart]
Save DANL as the reference trace for the
following DANL subtraction
[Trace/Detector] {Select Trace} {Trace 2}
{More 1 of 2} {Copy/Exchange} {From Trace}
{Trace 2} {To Trace} {Trace 3} {Copy Now}
Implement DANL subtraction
[Meas Setup] {More 1 of 2} {Cancellation}
{Cancellation On} {Ref Trace} {Trace 3};
[Meas Setup] {Meas Type} {Phase Noise}
[Single]
Figure 6. DANL measurement result
Figure 7. Phase noise plot with DANL subtraction

Additional Resources
Web
Product page: www.keysight.com/nd/n9068a and
www.keysight.com/nd/w9068a
X-Series signal analyzers: www.keysight.com/nd/X-Series
X-Series advanced measurement applications:
www.keysight.com/nd/X-Series_apps
Literature
N9068A & W9068A Phase Noise Measurement Application Technical
Overview, literature number 5989-5354EN
N9068A & W9068A Phase Noise Measurement Application
Measurement Guide, literature number N9068-90011
Phase Noise Measurement Selection Guide, literature number
5990-5725EN
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This information is subject to change without notice.
© Keysight Technologies, 2011 - 2014
Published in USA, August 1, 2014
5990-8014EN
www.keysight.com
08 | Keysight | N9068A & W9068A Phase Noise X-Series Measurement Application – Demo Guide
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