Agilent NFA Series Noise Figure Analyzers

Agilent NFA Series Noise Figure Analyzers
Agilent
NFA Series
Noise Figure Analyzers
Demo Guide
Agilent Technologies
Table of Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Front panel overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Rear panel overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
How the front panel keys are organized . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Navigating through the menu system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Demo kit layout and parts list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Basic noise figure measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Section 1 Entering the ENR table for a noise source . . . . . . . . . . . . . . . . . . . .11
Section 2 Calibration of the noise figure analyzer . . . . . . . . . . . . . . . . . . . . . .15
Section 3 Basic noise figure and gain measurements . . . . . . . . . . . . . . . . . .17
with an amplifier as the DUT
Section 4 User interface display features . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Section 5 File management functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Advanced noise figure measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Section 6 Speeding up measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Section 7 Frequency multiplier mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Section 8 Frequency dependent loss compensation mode . . . . . . . . . . . . . . .33
Section 9 Manual measurements mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Section 10 Narrowband noise figure measurements . . . . . . . . . . . . . . . . . . . .38
with a filter as the DUT
Section 11 Noise figure measurements with a mixer as the DUT . . . . . . . . . .40
Section 12 Noise figure measurements with a mixer as part . . . . . . . . . . . . .42
of the measurement system
Section 13 Printer setup/landscape/portrait . . . . . . . . . . . . . . . . . . . . . . . . . . .44
Section 14 Help mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
2
Introduction
This demo guide will help you
gain familiarity with the basic
and advanced features and functionality of the NFA series noise
figure analyzers. The demo guide
is to be used with the NFA demo
kit Option K13, which is available from the South Queensferry
Specials Department.
All demonstration exercises in
this guide require an Agilent
SNS Series N4002A noise source.
This noise source is not included
in the NFA demo kit, option K13,
and must be ordered separately.
3
This demo guide is consistent
with NFA firmware revision
A.01.01
For more information on the
Agilent NFA series noise figure
analyzers or SNS Series noise
sources, including links to
the product support pages,
see our web page at:
www.agilent.com/find/nfa
Front panel overview
3
4 5
6
7
13
12
11
10
8
2
1
20
19
18 17
16
15
14
Figure 1. Front panel overview
4
9
Table 1.
Front panel items descriptions
Item
1
Description
The On key turns the NFA on, while the Standby key switches the NFA to stand
by mode.
After turning on the NFA, with the factory default Alignment running, allow
60 minutes of warm-up time to ensure the NFA meets its specifications.
2
Viewing angle keys allow you to adjust the display so that it can be optimally
viewed from different angles.
3
The ESC (escape) key cancels any entry in progress. ESC aborts a print
(if one is in progress), clears error messages from the status line at the
bottom of the display and clears input conditions.
4
Menu keys are the unlabeled keys along the right side of the display. The menu
key labels, which identify the current functions of these keys, are shown on the
screen next to the keys.
5
The MEASURE functions allow you to configure the measurement mode and set
the NFA parameters needed for making measurements.
The Frequency/Points and Averaging/Bandwidth keys activate the primary set
up function keys and access menus of related functions.
The Calibrate key removes any second stage noise contribution from the
measurement. The ENR key accesses the ENR menu, from which you can enter
the ENR data.
The Meas Mode and Mode Setup keys are used to configure the NFA to
measure mixers and frequencies greater than the basic frequency of the NFA
using a local oscillator.
6
The DISPLAY functions allow you to configure the display results.
The Scale key sets the scale of the graph results. The Format key allows you to
set the format of the result. The Marker key allows you to control the markers
and search the trace. The Result key is used to select the desired measurement
parameters.
7
The CONTROL functions control the NFA’s setup of Loss Compensation and
Limit Lines. The Corr key sets correction and input calibration ranges. The
Sweep mode is controlled in this group, as is full screen display. The Full
Screen functions in all display formats.
8
SYSTEM functions affect the state of the noise figure analyzer. Various setup
and alignment routines are accessed with the System key.
The green Preset key resets the noise figure analyzer to a known state.
The File key menu allows you to save and load traces, ENR tables, limit-line
tables, and frequency lists to or from the NFA memory or the floppy disk drive.
The Save Trace key executes the Save function defined under File.
The Print Setup menu keys allow you to configure hardcopy output. The Print
key sends hardcopy data to the printer.
5
Table 1.
Front panel items descriptions (continued)
Item
Description
9
The media door on the right side of the front panel accesses the 3.5-inch disk drive.
10
The data entry keys, which include the up/down arrow keys, knob, and numeric
keys, allow you to enter or change the numeric value of an active function.
The numeric keys permit entry of exact values for many of the NFA functions. To
terminate a numeric, where no unit labels have been presented, press the Enter key.
The knob allows continuous change of functions such as center frequency,
averages, and marker position.
The up/down arrow keys allow discrete increases or decreases of the active
function value.
11
EXT KEYBOARD. The EXT KEYBOARD connector is a 6-pin mini-DIN connector
for future use with PC keyboards. It is not currently supported.
12
PROBE POWER provides power for accessories.
13
The Prev key accesses the previously selected menu.
Continuing to press Prev key takes you to earlier menus in the present menu
system.
14
NOISE SOURCE DRIVE OUTPUT +28 V PULSED this connector provides a 28 Vdc
level to switch the noise source on. The noise source is off when no voltage is
applied. To be used with 346 noise sources.
15
Tab keys are used to move between table input fields, and to move within the
fields of the dialog box accessed by the File menu keys.
16
INPUT 50 Ω (ESD sensitive) is the signal input connector for the NFA.
17
The
is active.
Next Window key selects which graph or result parameter
Pressing the
Zoom key while in graph mode switches between
the dual graph and single graph to display the active graph.
18
Press the Help key and then any front panel or menu key to get a short description of the key function and the associated remote command. The next key you
press removes the help window from the display.
19
The On key turns the NFA on, while the Standby key switches the NFA to
standby mode.
After turning on the NFA, with the factory default Alignment running, allow
60 minutes of warm-up time to ensure the NFA meets its specifications.
20
SNS series noise source connector allows the use of the new SNS series
noise sources with the NFA series.
6
1
Rear panel overview
2
3
4
5
6
11
10
9
Table 2.
Rear panel items descriptions
13
12
8
7
Figure 2. Rear panel overview
Item
Description
1
Input connector for the AC line-power source. Make sure that the line-power .
source outlet has a protective ground contact.
2
Line Fuse. The line fuse is removed by twisting counterclockwise 1/4 turn.
Replace only with a fuse of the same rating. See the label on the rear panel.
3
Service Connector. The service connector is for service use only.
4
VGA OUTPUT drives an external VGA compatible monitor with a signal that
has 31.5 kHz horizontal, 60 Hz vertical synchronizing rates, non-interlaced.
5
PARALLEL interface port is for printing only.
6
RS-232 interface supports remote instrument operation.
7
10 MHz REF IN accepts an external frequency source to provide the 10 MHz,
-15 to +10 dBm frequency reference used by the NFA.
8
10 MHz REF OUT provides a 10 MHz, 0 dBm minimum, timebase
reference signal.
9
LO GPIB port is for the control of an external LO by the NFA.
10
MAIN GPIB interface port supports remote instrument operation.
11
AUX OUT (TTL) is not currently supported.
12
AUX IN (TTL) is not currently supported.
13
Power On Selection selects an instrument power preference. This preference
applies after power has been absent for >20 seconds. The PWR NORM
position causes the instrument to remain off when power is applied.
The PWR ALWAYS ON position causes it to turn on. The PWR ALWAYS ON
mode is useful if an external power switch is used to control a rack of
several instruments.
7
How the front panel keys
are organized
The front panel keys are divided
into four main groups:
•MEASURE keys, which are
used to configure the
measurement parameters,
such as frequency range,
bandwidth, and number of
measurement points.
• CONTROL keys, which are
used to configure advanced
measurement parameters,
such as Loss Compensation
and Limit Lines.
• SYSTEM keys, which perform
system-level operations such
as configuring the NFA’s GPIB
address, displaying status
information and configuring
an external LO.
• DISPLAY keys, which adjust
the display characteristics of
the measurement; for example,
setting which parameters are
displayed, Selecting the display
format (graph, table or meter),
and adjusting the scaling.
8
In addition to the four main
groupings, the keys are also
further grouped according to
key size and proximity to the
display. The large keys placed
in the column nearest the display
(Frequency/Points,
Averaging/Bandwidth, Calibrate,
Scale and Format) are typically
the keys that are used most
frequently when performing
a measurement.
Action keys
Pressing any of the white action
keys (Calibrate, Full Screen,
Restart, Save Trace and Print)
invokes an action.
Navigating through the
menu system
Menu Keys
Pressing any of the grey front
panel keys in the MEASURE,
DISPLAY, RESULT or SYSTEM
key groupings (see Figure 3b)
accesses menus of key labels
that are displayed along the
right-hand side of the display.
The unmarked keys located to
the right of the display activate
the functions indicated by
these labels (Figure 3a). These
unmarked keys are called
menu keys.
To activate a menu key function
To activate a menu key function,
press the menu key immediately
to the right of the corresponding
menu key screen label. The menu
key labels that are displayed
depend on which front panel
key is pressed and which menu
level or page is selected.
menu key labeled Start Freq,
“Start Frequency 10.00000000
MHz” appears in the active
function area and this key’s
label is highlighted. The Start
Frequency can be changed using
any of the data entry controls
and the numeric section of this
display will change to suit.
When a menu key function is
selected, it is called an active
function. The key label of the
active function is highlighted
after that key is pressed. For
example, if you press the Frequency/Points key, the menu of
related configuration parameters
appears. If you now press the
Menu keys activate functions
other than those accessed
directly by the front panel keys.
Figure 3b. Front panel keys
Figure 3a. Menu keys
9
Demo kit layout and
parts list
This section includes a part
layout map (Figure 4) that
shows where all NFA demo kit
components are placed within
the demo kit. Part numbers are
also shown. This part layout
map can also be found on
the inside of the demo kit lid.
The standard 50-ohm BNC cable
for use with a 346 series noise
source or 11730A can be found
in the main shipping box of the
N8975A and for convenience can
be placed in the relevant section
of the demo kit.
The SNS Series N4002A noise
source, which is required to
make all noise figure measurements, is not supplied with this
demo kit and must be ordered
separately.
The parts contained in the kit
are all readily available, and
each part number is displayed
directly in the relevant demo
kit aperture along with a
description of the part.
To order an Option K13 demo
kit for use with an N8975A
26.5 GHz noise figure analyzer,
contact the South Queensferry
Specials Department.
Power supply connector part number's 5040-0494 and 5060-0466
Mini circuits filter
SBP-70
SNS Noise Source
Mini circuits
mixer
ZFM-4212
Mini circuits
amplifier
ZFL-1000LN
SMA
to
BNC
connector
1250-1250
5/16" spanner
1m BNC 50 Ohm cable
Figure 4. Demo kit part layout map
10
2 x SMA connector
46101-60039
8720-0015
Basic noise figure
measurements
Section 1.
Entering the ENR table for
a noise source, manually or
automatically
For other noise sources, a disk
containing the ENR data and
the identification/serial number
of the noise source can be
created.
All demonstrations require an
Agilent N4002A noise source.
The N4002A is not included in
the NFA demo kit and must be
ordered separately.
Key names surrounded by [ ]
indicate labeled hard keys
located on the front panel, while
key names surrounded by { }
indicate menu keys (soft keys)
located along the right edge of
the display.
Objectives:
• Enter an ENR table or modify
an existing one.
• Save the ENR table to hard
disk and floppy disk.
The ENR data for the noise
source is used to calibrate the
noise figure measurement system. Calibration removes the
system’s own noise figure from
the measurement.
Figure 5
The New SNS series noise
sources only require a connection to the NFA via an 11730A
cable to automatically transfer
the ENR data to the NFA.
Since November 1, 2000 the
Agilent 346 series noise sources
have come with a disk containing
the noise source ENR data to
allow quicker and easier calibration of the noise figure analyzer.
The NFA will automatically load
the ID and serial number of the
noise source when loading the
ENR data from the disk.
Figure 6
11
To enter an ENR table manually,
press [ENR]. The analyzer will
display the screen shown in
Figure 5.
The SNS series are broadband
noise sources designed specifically for use with the NFA.
The SNS series can be used in
conjunction with the NFA to
increase the overall reliability
and accuracy of noise figure
measurements. The SNS series
noise sources have the advantage
of automatic ENR data upload as
well as automatic temperature
sensing to automatically sense
the ambient temperature of the
measurement environment,
allowing the NFA to compensate
for the these changes during its
measurement cycle to maintain
accuracy.
By setting the preference for
ENR data to SNS means that
whenever the SNS series noise
source is present, then the SNS
data will be used as the current
ENR table.
If a value in the table is to be
modified, highlight it with the
yellow bar using the relevant
navigation menu keys or Tab
keys and then enter the value
via the keypad. The “cardinal”
frequency points from the noise
source need not be entered in
order, since after being entered
they will be automatically
aligned in ascending order.
You can also have two separate
ENR tables, one for calibration
and one for measurement. These
can be selected by toggling
[ENR]{Common Table} to Off.
When this has been done, the
NFA will use a different ENR
table for calibration than the
one used for the measurement.
The default is to use one table,
the measurement table.
Upon startup, the most recently
used ENR file is recalled and
used as the default ENR. This
file survives a Power cycle or a
Preset and can be replaced at
any time with a file of your
choice. Upon next startup your
new file will be recalled as the
default file.
With two ENR tables, the user
can calibrate with one noise
source, removing the noise figure
measurement system’s own noise
figure (often referred to as second stage noise contribution),
and then use another noise
source for the measurement.
To check the data has been
loaded view the ENR table
editor screen as the data from
the SNS automatically replaces
the data used before. This also
includes the serial number and
model number.
To edit the ENR table, manually
toggle the {Edit Table} menu
key. Similarly, the serial number
and ID number can be edited by
toggling the appropriate menu
key. The Tab hard key or the
navigation menu keys at the
side of the measurement window can then be used to scroll
down the table (see Figure 7).
Figure 7
12
The two most common cases in
which two noise sources and
two ENR tables are used are
as follows:
In the most common case, you
have a waveguide noise source
for measuring noise figure and
gain at microwave frequencies.
There is no way to calibrate
your measurement system with
a waveguide connector at lower
frequencies. In this case, you
first enable the two measurement tables located within the
NFA. Under the [ENR] hard key
there is a soft key for {common
Table}; toggle this soft key to
Off. The next step is to load the
two ENR tables, first the lower
frequency one for the calibration
and then the waveguide ENR
table for the measurement. The
tables can be loaded either manually or by using the file manager and the ENR data disks supplied with your noise sources.
After the ENR data has been
entered, connect the lower frequency noise source to calibrate
the measurement system over its
10 MHz to 3.0 GHz range. After
the calibration is complete, connect the waveguide noise source
to the DUT and make the measurement.
The second case is measuring a
DUT with a low noise figure and
a high gain, such as an amplifier.
In this instance also, two separate ENR tables must be entered,
and the [ENR]{Common table}
soft key must be toggled to Off
to allow the use of the two ENR
tables during calibration and
measurement. In this case, a
high ENR source such as an
N4002A (ENR of about 15 dB)
should be used for calibration.
Once the calibration is completed, a low ENR source such as
the N4000 (which has an extra
10 dB pad on its output and a
6 dB ENR) can be used. The
Agilent N4000 is designed
specifically for accurate characterization of input-impedancesensitive devices, such as GaAs
FETs and many UHF amplifiers.
Its very small change in reflection coefficient (<0.01) from on
to off minimizes errors when
measuring noise figure and gain.
13
Instructions
Keystrokes
Auto upload of ENR data from
SNS series noise source
[ENR] {SNS Setup} {preferences}
toggle to On {Autoload ENR} toggle to On
Connect SNS to NFA using the
11730A cable
No key presses required
Check data has transferred
[ENR] {ENR table}
Recall (load) an ENR table
from ENR data disk
(automatically) when using a
346 series noise source
Insert ENR data disk into 3.5” slot in
NFA and close the door.
[File] {Load} {ENR Meas table} [ ⇒| ] or
if file directory “..” is already highlighted
press {Select}, then use [⇑] or [⇓] to
highlight the “A” directory one {Select} ??
Select the ENR file using [⇑] or [⇓]
the [Enter] to the load the file.
Review loading of table,
ID number and serial number
[ENR] {ENR Table}
Enter the ENR menu (manually)
[ENR]
Enter the ENR table mode
{ENR Table}
Insert/Modify the ENR table values,
serial number and ID number
If this is the first ENR data entry after
a firmware install, there will be no entries
present in the ENR table. To enter values
in the table editing mode, press {Add}
before commencing manual data entry
If {Edit Table} or a Tab key is pressed,
the ENR table-editing mode will
be entered. The ENR menu keys can then
be used to select the field to be modified.
Use the keypad to modify and choose
appropriate units, To enter serial number
data {Prev}{Serial Number}, then use the
keypad, menu keys and numeric keypad to
modify. To enter ID number data {Prev} {ID},
then use the keypad, menu keys and
numeric keypad to modify.
To Save the ENR table
1. Call up the file save menu
[File] {Save} {ENR} {Meas table}
2. Choose internal memory
drive or floppy disk
[ ⇒| ] or if file directory “..” is already
highlighted press {Select}, then use [⇑] or [⇓]
to either highlight the “C” or “A” drive,
then {Select} to confirm directory choice.
3. Enter the file name using
alpha editor
Highlight the Name: section by using the
[⇐] key, then Enter a file name using
alpha menu keys and/or number keys.
4. Save into internal memory
[Enter] to save [Bk Sp] if an error is made
during file name editing.
14
Basic noise figure
measurements (continued)
Section 2.
Calibration of the noise
figure analyzer
NFA series noise
figure analyzer
Top of unit front
panel
Noise source
Figure 8. Calibration setup
50-ohm
coax cable
Objectives:
• Calibrate the NFA to make
basic NF measurements with
the supplied DUT.
For a correct measurement of
noise figure for a device under
test, the system must first be
calibrated. This calibration is
necessary because the measurement system itself has a noise
figure at each of the noise figure measurement points. This
noise figure is referred to as
second stage noise contribution.
The processor inside the noise
figure analyzer measures the
measurement system’s own
noise figure and then removes it
from the measurement, so that
only the DUT’s noise figure and
gain will be displayed. (The gain
of the measurement system is
always displayed in a “corrected” state.) Connect the system
as shown in Figure 8.
Set the initial Start and Stop
frequency parameters according
to the DUT to be used. In this
case, the Mini Circuits amplifier
in the NFA special Option K13
demo kit. Some averaging points
15
can also be added in the calibration sweep. This can improve
measurement accuracy by
smoothing out display jitter and
helping to remove nonlinearities
in the DUT output trace.
After entering your ENR data,
frequency data, averaging and
measurement bandwidth specifications, start calibration by
pressing [Calibration]
[Calibration]. This will set the
system to sweep across the userset frequency range five times,
with a different attenuator setting for each sweep. This frequency/attenuator sweep will
enable the correct noise figure
of the system to be measured at
each of the measurement points.
Once the calibration sweep has
been completed, the display
shows a single frequency sweep
in which the system’s noise
figure is removed from the
measurement system and the
displayed noise figure of the
measurement system is approximately zero. The analyzer is
now calibrated and can make
“corrected” noise figure
measurements.
Instructions
Keystrokes
Connect N4002A noise source
As shown in diagram
Save the Calibration Frequency Span
1 Call up the
Frequency/Points menu
[Frequency/Points]
2 Enter the Start Frequency
{Start Freq.} 10 enter by keypad {MHz}
which is the default value
3. Enter the Stop Frequency
{Stop Freq.} 1.2 enter by keypad [GHz]
4. Set the number of points at
which to measure
{More 1 of 2} {Points} 11
To modify, enter value by keypad
[Enter] [bkspace] if an error is made
Set the Averaging function to a
point sweep with 15 averages
[AVG/BW] {Average} Toggle to On
{Averages} 10 set by keypad
[Enter] [Average/Bandwidth]
{Averaging} toggle to ON
{Averaging mode} toggle to
Point (Default)
Select format for viewing
of measurements
[Format] {Format} personal choice
of display
Calibrate measurement system
[Calibrate] [Calibrate]
16
Basic noise figure
measurements (continued)
Section 3.
Basic noise figure and gain
measurements with an
amplifier as the DUT
Objectives:
• To make basic NF and gain
measurements with the
supplied amplifier DUT.
The NFA demo kit is supplied
with a Mini-Circuits amplifier,
which has its power supplied by
the probe power supply on the
front panel of the NFA.
Follow the instructions below to
obtain the output display shown
in Figure 9.
Since the measurement system
has already been calibrated to
sweep across the useable range
Figure 9
17
of the DUT, a basic noise figure
measurement requires the DUT
to be plugged in between the
noise source and the NFA
and the amplifier power connector to be connected to the NFA
probe power supply. As soon as
the DUT is connected the system will begin sweeping, measuring the noise figure and gain
of the amplifier.
The choice for a single sweep or
continuous sweeps across the
prespecified frequency range can
be found under [Sweep] on the
front panel.
Instructions
Keystrokes
Calibrate the system
Completed during previous section
Choose sweep parameters
[Sweep] Toggle to {single}
or {continuous}
Connect the amplifier DUT and
make the measurement
As per Figure 8, if on single sweep
then hit [Restart]
View the results
[Format] {Graph}, {Table} or {Meter}
Change the scaling on the
measurement window
[Scale] {Autoscale} [Active window select]
to change the scaling for gain also
[Scale] {Autoscale}
18
Basic noise figure
measurements (continued)
Section 4.
User interface display
features
Objectives:
• Fully demonstrate the NFA’s
user interface/display
functionality through the
following features:
Select and Zoom Active
Window
Change Scaling
Place Markers
Change Measurement Format
Full Screen Expandable
Display
Change Format of
Active Window
Create and Test to
Limit Lines
Data to Memory Function
Swap and zoom active windows
The graphical display on the
NFA can show simultaneous
measurement of two parameters
in separate measurement windows. To see one window more
closely, press the Next Window
key till the appropriate window
is active (a green border appears
around the selected window),
then press [Zoom] to enlarge
the active window to full screen.
Pressing [Zoom] once more
19
restores the previous twin graph
display. To display the other
graph full screen if you are
already viewing one measurement
window in the full screen mode,
press the Next Window key.
Change scaling
When viewing measurements
in a graphical mode it is often
beneficial to change the viewing
scale to make analysis of the
measurements easier. Although
the NFA comes with an autoscale function, the ability to
change the scale of both graphs
or add reference levels separately is made available by pressing
[Scale].
Measurement mode set-up
The measurement correction
guide present on the noise figure
analyzer is a basic guide to aid
you in making the connections
for your measurement scenario.
The feature can be found by
pressing [Meas Mode]. To change
the measurement connection diagram for your application, simply
select the type of DUT you would
like to measure and the display
shall change to show the basic
connection states for both the
measurement and the calibration.
Figure 10a. The set-up screen for an amplifier measurement, (this is the default mode on the analyzer)
Figure 10b. The example Basic connection diagram for a DUT as a down converter showing
complete Cal and measurement diagrams.
20
Swap and zoom
active windows
Change scaling
Instructions
Keystrokes
Swap active window in display.
[
]
Zoom in on active window
(and swap if applicable)
[
] if applicable [
Return to previous two-window view
[
]
Instructions
Keystrokes
]
Change Scaling
Autoscale
[Scale] {Autoscale}
Manual change (if applicable)
[Scale]
1. Change measurement units
[Scale] {Units} toggle between
linear/logarithmic
2. Change the upper limit
{Upper Limit} enter value by keypad [Enter]
3. Change the lower limit
{Lower Limit} enter value by keypad [Enter]
4. Set a reference level (if desired)
{Ref Level} enter value by keypad [Enter]
Enable/Disable Ref level
21
[Scale] {Ref level} toggle function On/Off
Place Markers
The NFA series offers true
analyzer functionality, through
its many features, one of these
features is the marker functionality. The values for consecutive
noise figure and gain at a specific point chosen by the RPG can
be read off quickly and easily.
The gap above the twin graph
display has been utilized to show
a simple table for displaying the
marker information, allowing
clear and precise marker
labelling data with respect to
Frequency, amplitude and
Marker number as well as
marker type.
The search functions work,
as you would expect, with the
ability to search for either minimum or maximum values within
the trace. This sweep can be in
either continuous mode or
single mode.
Figure 11
When [Marker] has been pressed,
the submenu will appear as
shown in Figure 11. To activate a
marker, press the “Marker” menu
key. Since marker 1 is already
enabled, toggle the {State} menu
key till “normal” is present. The
marker should now appear on
the screen at its default point. By
using the knob, you can place
the marker wherever you want.
You can follow this procedure to
enable any of the markers by
toggling {Marker} till the marker
of your choice is underlined and
toggling the {State} key until
“normal” is highlighted.
22
Only traces 1 and 2 can be shown
in the top measurement window,
and only traces 3 and 4 can be
shown in the bottom measurement window. The display in
Figure 11 also shows the Marker
“Delta” function (for markers
4 and 4R), which shows the
difference between two user-set
points. These points can be set
by first placing one marker manually, then enabling the function
[State] {Delta} and using the
manual controls to set the
second marker’s delta position.
The delta value is displayed on
the screen.
Place Markers
Instructions
Keystrokes
Enable Marker submenu.
[Marker]
Choose Marker to be set,
(up to four can be displayed
at any one time), then display it.
{Marker} toggle to {1} {State} {Normal}
then vary position of marker via
KNOB or up/down keys.
Follow this procedure for the other
markers as well.
View displayed result
The Marker display at the top of the
main screen shows the measurement
and the marker’s position
Search for min/max points
{Search} Toggle {Search type} to
Min or Max via menu key, then
{continuous} toggle to On to find point.
Or otherwise {Continuous} toggled
to Off and then {Find}
In the NFA there are three different display formats available: Graphical Display mode,
Table mode and Meter mode.
The Table format is shown in Figure 12.
Change format of
active window
Instructions
Keystrokes
Enable Graphical Display mode
[Format] {Graph} this is displayed as default
Enable Table mode
[Format] {Table}
Enable Meter mode
[Format] {Table}
Figure 12
23
If you do a single sweep and the
measurement points continue
off of the first screen, use the
tab keys to alternately view the
first or second screen of measurement points.
The Meter format gives a simple
display, as shown in Figure 13
with a measurement made at a
single frequency point.
To change the fixed frequency
value found in this mode,
press [Frequency/Points]
{Freq Mode}{Fixed} then
{Fixed Frequency}, numeric
keys to enter the frequency
value, followed by units, then
[Calibrate] [Calibrate].
Change measurement factor
By default the noise figure analyzer will display noise figure
and gain measurements, but
there is a separate function for
displaying different measurements, found under [Results].
The choices for displayed measurement format are shown in
Figure 14.
Figure 13
Depending on which measurement factor is chosen and
which window is active (green
border), the graphical, table, or
meter mode labeling will also
change to suit.
Figure 14
24
This function can be implemented by pressing [Full Screen] in the Control menu. It is also possible to
turn off the graticule, annotation and menu key labels, this shows how versatile the NFA’s measurement
display window is.
Full screen
expandable display
Instructions
Keystrokes
View the measurement
window full screen.
[Full Screen]
View the measurement
window with menu keys.
[Full Screen]
View the display
without annotation.
[Format] {Annotation} toggle to Off
Turn the graticule off.
[Format] {Graticule} toggle to Off
Turn the annotation and
graticule back on.
[Format] {Graticule} toggle to On,
{Annotation} toggle to On
Create and test to limit lines
In the manufacturing environment, it may be necessary to
increase measurement throughput. This could be implemented
by inserting pass/fail limit lines.
By using this function, the operator can quickly and efficiently
quantify noise figure and gain,
dramatically reducing time
spent per DUT.
When the DUT is connected
to the noise figure analyzer,
a simple pass-fail limit, called
a mask, can be placed around a
particular noise figure or gain
level. If the noise figure or
gain is above or below this
level, beyond the boundaries
of the mask, then the device
will be considered to have
failed the test. This device
failure will cause the system
to show a “Limit Fail” indicator
on the display.
Figure 15
25
The limit line editor allows you
to disconnect selected points,
breaking the limit line across
sections of the measured frequency span that you want to
exclude from the test.
The table should look like the
one in Figure 15 after you modify
it. Figure 16 shows the “Limits
Fail” indicator in the top left
hand side of the screen, which
appears when the DUT measurement does not stay within the
user-defined limit lines.
These limit line values are
stored during a state save or
by saving a specific limit line.
Figure 16
Note: You can put the points in
any order and the NFA will
auto-sort them into ascending
order.
Instructions
Keystrokes
Set upper limit
[Limit Lines] {Type} toggle to
“upper” (as default)
Enter 7 different measurement points to
produce an “upper” limit line only.
Ensure that noise figure is the active
window in the graphical display mode.
N.B. Limit lines can be saved and
recalled for demo purposes.
{Editor} {Add} 10 by keypad {MHz} [⇒|]
3.2 by keypad {x1} [⇒|] [⇒|]
100 by keypad {MHz} [⇒|]
3.2 by keypad {x1} [⇒|] [⇒|]
600 by keypad {MHz} [⇒|]
2.4 by keypad {x1} [⇒|] [⇒|]
800 by keypad {MHz} [⇒|]
3.2 by keypad {x1} [⇒|] [⇒|]
500 by keypad {MHz} [⇒|]
3.2 by keypad {x1} [⇒|] [⇒|]
1.0 by keypad {GHz} [⇒|]
3.2 by keypad {x1} [⇒|] [⇒|]
{Row down} {Row down} {Row down} [|⇐]
1.2 by keypad {GHz} [⇒|]
3.3 by keypad {x1}
Connect points together or not
Yes is default, use the arrow keys to deselect
when in “connected” column
Turn Limit Line Display ON
[Limit Lines] {Display} toggle to On
Turn limit test ON to invoke a
“Fail” on the display
[Limit Lines] {Test} toggle to On
26
The values for frequency and
limits should be entered via
the keypad, followed by the
relevant menu key for its value.
To disconnect a point from the
previous one, toggle the
up/down arrow keys till
“NO” is highlighted.
Data to memory function
A production line may use a
“gold” DUT as a reference to set
known operating parameters
for their instruments. The Data
to Memory function simplifies
this process. This function allows
a “snapshot” of a trace to be
saved and then displayed at
will. In this way, the parameters of a “gold” DUT can be
compared against a current
measurement, as illustrated
in Figure 17.
Figure 17
Pressing the {Data to Memory}
menu key will automatically
save the current trace data,
such as a reference measurement of a “gold” DUT, in the
memory. The device to be
compared with the “gold” DUT
is then measured. The user can
display the saved reference
trace only, the current trace
only, or both traces together
to compare them.
Instructions
Keystrokes
Select the Data to Memory function
[Format]
Save the current trace
{Data to Memory}
Display the saved trace on the screen
{Trace} {Memory}
Display both the saved trace and the
current trace on the screen
Trace {Both}
27
Basic noise figure
measurements (continued)
Section 5.
File management
functionality
Objective:
• Show the manipulation of
system states, traces and
screen dumps (that is, the file
management functionality of
the NFA family of noise
figure analyzers).
The saving of ENR data is covered above in Section 1, but
there are other file management
functions available under the
[File] hard key.
It is possible to save CORRECTED
instrument state setups, limit
line settings, the frequency list
and GIF format screen dumps.
It is also possible to quick-save
files after an initial save of any
of the possible parameters has
been carried out through the file
management functions. Pressing
the [Save Trace] hard key will
execute a quick-save to the same
directory in which the previous
trace was saved and automatically increment the filename
to preserve your existing files
(for example, a Trace file
TST0001.CSV is incremented
to TST0002.CSV).
28
If you save a system State, either
corrected or uncorrected, the
data for ENR, frequency lists,
limit lines and also GPIB
settings for LO control parameters are all stored and can be
recalled. Be careful to connect
the corresponding noise source
and DUT when calling up a
corrected system state. These
parameters can all be saved separately, too. The GPIB control
parameters survive both preset
and power cycles.
The trace files are in a .csv
format to enable import into
spreadsheet packages such as
Microsoft® Excel to enable multiple overlays of traces to be displayed or printed. The frequency
list, limit lines and ENR data can
all be modified or displayed via
a text editor such as Microsoft
Windows® Notepad or Wordpad
before re-import.
Instructions
Keystrokes
Enter the File Management menu
[File]
Save instrument State/Frequency List/Trace
1. Call up the file save menu
{Save}, {State} or {Frequency List} or {Trace}
2. Enter the file name using
alpha editor
Enter a file name using alpha menu
keys and/or number keys,
3. Choose internal memory
drive or floppy disk
[⇒|] or if file directory “..” is already
highlighted press {Select}, use [⇑] or [⇓]
to highlight the “C” or “A” drive, then
{Select} to confirm directory choice.
4. Save
[Enter] to save
Recall (load) a system State,
Frequency List
[File] {Load} {State}, {Frequency list} or
{Trace} highlight file name with KNOB, [⇑],
or [⇓] pressing select to choose the
drive to load from then [Enter] to load.
Save pass/fail Limits
1. Call up the file save menu
[File]{Save}, {Limits} then {1}, {2}, {3} or {4}
2. Enter the file name using
alpha editor
Enter a file name using alpha menu keys
and/or number keys,
3. Choose internal memory drive
or floppy disk
[⇒|] or if file directory “..” is already
highlighted press {Select}, use [⇑] or [⇓]
to either highlight the “C” or “A” drive,
then {Select} to confirm directory choice.
4. Save
[Enter] to save
Recall (load) pass/fail Limits
[File] [Load] {Limits} then {1}, {2}, {3} or {4}
highlight file name with KNOB,[⇑], or [⇓]
then [Enter] pressing {select} to select the
A or C drive. Then toggle the {Display}
under the [Limit Lines] menu key to Off
then ON to display limit lines.
Save Screen
1. Call up the file save menu
[File] {Save}, {Screen}{ Bitmap} or {Metafile}
2. Enter the file name
using alpha editor
Enter a file name using alpha menu keys
and/or number keys,
3. Choose internal memory drive
or floppy disk
[⇒|] or if file directory “..” is already
highlighted press {Select}, use [⇑] or [⇓]
to highlight the “C” or “A” drive, then
{Select} to confirm directory choice.
4. Save
[Enter] to save
29
Advanced noise
figure measurements
Section 6.
Speeding up measurements
Objective:
• Show the ability of the NFA
to make rapid discrete noise
figure measurements using
the Point or Sweep Averaging
and Frequency List modes.
Point or sweep averaging modes
The averaging mode can be
turned either On or Off. There
are two averaging modes available, Point and Sweep. In the
{Point} mode, the analyzer carries out all of the averaging at a
single point before moving on to
the next point. In the {Sweep}
mode, the analyzer takes a single
reading at a frequency point
before moving on to the next
frequency measurement point.
When it gets to the last point it
repeats from the first measurement point, averaging the new
reading with the recorded first
reading, building up successive
averages over time. This sweep
mode allows the real-time tuning of DUTs by allowing changes
to be shown on the screen as
they happen.
Instructions
Keystrokes
Enable/disable averaging mode
[AVG/BW] {Averaging} Toggle to On/Off
Enter the number of Averaging points
Use the keypad or knob followed by Enter
Choose format of Averaging
{Average mode} toggle to either {Point}
or {Sweep}
30
Frequency list and fixed
frequency modes
Another handy function provided in the NFA is the Frequency
List function. In the manufacturing environment it is possible to
increase throughput by only calibrating a measurement at a few
frequency points within the
DUT’s frequency span. Normally
the user specifies the start and
stop frequencies and then the
number of points to be measured. The instrument spaces
the measurement points equally
across the specified range. The
Frequency List function allows
you to manually set the measurement points, so that you are
not limited to equally spaced
frequency points but can measure at any frequencies in the
range. This capability is particularly useful when making
The NFA can fill in the table
for you: press {more 1 of 2}
then {Fill} when in the Freq
List editor.
measurements on DUTs such as
filters, where measurements at
specific points might be wanted
(for example, at the 3 dB points
or at several points where the
filter rolls off). Another situation
is when certain frequencies
should be avoided as they might
be a known source of interference while making measurements at these points.
The Fixed Frequency function
specifies only one point at which
to make a measurement. If you
need to make measurements at
one frequency (for example,
when measuring mixers with
a fixed IF and variable LO),
then this mode offers very
quick instrument setup and
measurements.
Instructions
Keystrokes
Insert Frequency List
[Frequency/Points] {Frequency mode}
{List} {More of 2} [Freq. List] Enter values
by navigating around table and using
{Add} followed by the frequency in Hz
menu key followed by [Enter] to enter
the value.
Enable new Frequency List function by
re-calibrating the instrument
[Calibrate] [Calibrate]
Plug in your DUT and then make
your measurement
Or alternatively, use the Fixed
Frequency function
Enable fixed frequency
calibration/measurement
Plug in your DUT and make
your measurement
None
31
[Frequency/Points] {Frequency mode}
{Fixed} [Prev]
{frequency} then use keypad to
modify followed by [Calibrate] [Calibrate]
None
Advanced noise
figure measurements
(continued)
Section 7.
Frequency Multiplier mode
The NFA Series has the capability of making noise figure measurements on devices which
have extra internal frequency
conversion using a multiple of
the initial LO frequency at it's
input. The LO multiplier should
be set to the multiple of the initial LO frequency used in the
initial set-up of the LO measurement parameters.
Instructions
Keystrokes
Change the LO multiplier value
[System] {External LO} {Multiplier}
enter numeric value by keypad then [Enter]
32
Advanced noise
figure measurements
(continued)
Section 8.
Frequency dependent
loss compensation modes
Objective:
• Show the ability of the NFA
to adjust for known losses
within the measurement path
or system for greater noise
figure measurement accuracy.
This function includes a before
and after DUT tables which can
list the losses within the measurement path at specific frequency points or allow you to
set a fixed loss which can be
used over the whole frequency
range of the sweep.
Figure 18
33
The noise figure analyzers
are able to directly load loss
compensation tables in the S2P
format used by network analyzers to automatically fill in the
relevant loss before or after
DUT tables.
To make the measurement
and maintain measurement
accuracy you will have to set
the ambient temperature at
which the loss occurs.
Loss compensation hard
key menu
There are often known losses
from cables or connectors in
your measurement path that
you may wish to compensate
for. With the NFA’s easy-toimplement loss compensation
functions, you can adjust your
measurement readings to be
more accurate.
Figure 19
Figure 20
34
Section 8.
Frequency dependent
loss compensation modes
(continued)
In this example we shall show
how to enter a fixed value of
Loss compensation before the
DUT and then use a table after
the DUT. This could be a relevant example when using a
mixer as a down converter. In
this instance the Mixer could
be classified using a network
analyzer or even the NFA using
the mixer as a DUT first, and
then use this information to
enter a table of losses after
the DUT. At the input where
the DUT may have a Pad for
Impedance matching and where
the loss may not change over the
measurement frequency range,
a fixed loss will then be entered
into the Loss before DUT table.
Figure 21
Instructions
Keystrokes
Enter the Loss Compensation mode editor
[Loss Comp]
Select Setup to use a fixed value of loss
compensation before the DUT
{Setup} {Fixed} [⇒|] enter 6 by keypad
{dB} [⇒|] enter 290 by keypad then {K}
Choose the type of loss compensation
before DUT to be a table
Use [⇒|] to scroll down to the After DUT
selection box then {Table}
Enter the temperature at which the
loss is occurring
Scroll up/down table using the tab key
[⇒|] to select “After DUT” temperature
Use keypad to enter 290 followed by {K}
Edit the after DUT table
[Loss Comp]
{After DUT Table}
10 by keypad {MHz} then
[⇒|] 6.5 by keypad {dB} [⇒|]
100 by keypad {MHz} then
[⇒|] 6.4 by keypad {dB} [⇒|]
200 by keypad {MHz} then
[⇒|] 6.6 by keypad {dB} [⇒|]
300 by keypad {MHz} then
[⇒|] 6.4 by keypad {dB} [⇒|]
400 by keypad {MHz} then
[⇒|] 6.3 by keypad {dB} [⇒|]
or use the Navigation keys instead
of the tab key [⇒|]
35
Advanced noise
figure measurements
(continued)
Section 9.
Manual Measurements Mode
This feature is for making either
manual measurements with
physical extremes of temperature, i.e a hot or cold source of
noise, or for users who use SNS
or 346 Series noise sources and
wish to control certain aspects of
the measurement sweep. These
measurements are more difficult
and slower than those made
automatically using the standard
measurement mode, a noise
source with an NFA. There are
no Physical extremes of temperature within the K13 NFA Demo
Kit, but this feature can be used
with and SNS Series noise source
for demonstration purposes.
Important notes when making
manual measurements:
1. A stable reading must be
stored in the NFA memory before
any change is made to the physical connections. A reading is
stored by pressing [Accept] in
the sequence before changing
connections.
2. The DUT must first be
connected to the measurement
system and then the NFA’s input
attenuators set. The input attenuators must be fixed for the
entire manual measurement by
toggling either {RF/µWAtt} to
Hold or {RF/µWAtt} to Fixed.
When using the fixed mode,
the fixed attenuator values
are specified using the Fixed
RF Att/Fixed µWatt menu keys.
3. The IF attenuators must be
allowed to autorange between
calibration and measurement.
36
4. The IF attenuators must be
held fixed for both calibration
readings (noise source on and
off) and also for both measurement readings (noise source
on and off) by selecting either
IF Att (Hold) or IF Att (Fixed).
When using the fixed IF mode,
the fixed IF attenuator value
is specified using the Fixed
IF Att menu keys.
5. When calibrating a series of
frequency points and an error is
made on one of the points, you
need to start calibrating the
series of frequency points again.
Press [Calibrate] to reset the
calibration.
6. When measuring a series of
frequency points and an error
is made on one of the points,
you need to start measuring the
series of frequency points again.
Press [Restart] to reset the
measurement.
7. If you set up the frequency
menu to measure a number of
points, then change the number
of points within the sweep,
(by pressing [Frequency/Points]
{More 1 of 2} {Points} and entering the value using the keypad
and then [Enter]. Then you
should repeat the measurement
procedure from the next measurement point until all the
points have been measured again.
8. The points need not be measured sequentially, they will
align numerically automatically.
A typical manual measurement
would be carried out as follows:
Instructions
Keystrokes
Connect the hot source, T hot, to the
DUT input, and the DUT output to the NFA,
(alternatively use an SNS or 346 noise
source) hold RF/µW attenuators for the
whole measurement.
{Noise Source} toggle to On, to measure
noise power with the source at T hot.
{RF/µWatt} toggle to Hold
Calibrate (with the noise source
Connected to the NFA).
{Calibration} toggle to On, to calibrate
with noise source at Phot.
{IF Att} toggle to Hold, to hold the
IF attenuators fixed at the new
value or use the previously defined
IF Att(Fixed) value.
{Accept} stores the Phot
calibration reading.
{Noise Source} toggle to off selects
the Pcold calibration reading.
{Accept} stores the Pcold
calibration reading.
{Calibration} toggle to Off
Measure (with the Noise Source
Connected to the DUT and the DUT
at the input of the NFA).
{Noise Source} toggle to On, selects
the Phot reading.
{IF Att} toggle to Auto, allows the
IF attenuators to autorange.
{IF Att} toggle to Hold, holds the
IF attenuators fixed at the new value
or uses the previously defined
IF Att(Fixed) value.
{Accept} stores the Phot
measurement result.
{Noise Source} toggle to Off
{Accept} stores the Pcold measurement
37
Advanced noise
figure measurements
(continued)
Section 10.
Narrowband noise figure
measurements with a filter
as the DUT
It must be noted that only the
N8973A, N8974A and N8975A
has a user-selectable measurement bandwidth. The N8972A
has a factory preset 4 MHz
measurement bandwidth.
Objective:
• Show the ability of the NFA
to make narrow bandwidth
noise figure measurements,
using a filter as the DUT.
NFA Series Noise
Figure Analyzer
Front
Mini Circuits
Amplifier
11730A
Cable
AMP
Probe Power
Mini Circuits
Filter
SNS Series
Noise Source
Figure 22
Figure 23
38
Section 10.
Narrowband noise figure
measurements with a filter
as the DUT (continued)
To obtain optimum noise figure
measurement accuracy, please
remember to measure with the
same bandwidth you used for
calibration.
Instructions
Keystrokes
Connect the noise source to the N8973A
As per Calibration diagram in Section 2
Enter the ENR table data for the
noise source
See Section 1
Set the Calibration Frequency Span
1. Call up the
Frequency/Points menu
[Frequency]
2. Enter the Start Frequency
[Frequency] {Start Freq} 52 MHz
set via keypad then [Enter]
3. Enter the Stop Frequency
[Frequency] {Stop Freq.} 88 MHz
set via key pad then [Enter]
4. Set the number of
measurement points
[Frequency] {More 1 of 2} {Number of
points} 15 by keypad then [Enter]
The NFA Series use DSP architecture to achieve very high
frequency accuracy and also to
reduce the time penalties usually involved in making this type
of measurement.
Select measurement Bandwidth
[Averaging/Bandwidth] {Bandwidth}
{400 KHz}
Enter number of Averages
to smooth display jitter
[Averaging/Bandwidth] {averages}
5 by keypad then [Enter] {Averaging} toggle
to ON {Average mode} toggle to Point
Calibrate the system
[Calibrate] [Calibrate]
There should also be noticeably
more display jitter when making
measurements with a bandwidth
less than 4 MHz on the NFA.
Connect noise source, filter and
amp to the NFA
As shown in diagram above
Select format for viewing
of measurements
[Format] {combined} toggle
to ON {format} {graph}
To maintain the same levels of
stability and final accuracy for
your measurement when using
narrower bandwidths, you
should use a factor of averaging
to compensate for the display
jitter. e.g you would have to use
40 times more averaging when
using a 100 KHz bandwidth than
you would if you were using a
4 MHz measurement bandwidth
and similarly 20 times the
amount of averaging required
for a 200 KHz bandwidth than
you would use in a 4 MHz
bandwidth
Change scale to view
optimal measurement
[Scale] Noise figure {upper limit}
25 (dB default units) enter by keypad
then [Enter] {lower limit} 0 enter by
keypad [Enter] [Next window] Gain 25,
enter by keypad then [Enter] {lower limit}
0, (dB default units) enter by keypad [Enter]
39
Advanced noise
figure measurements
(continued)
Section 11.
Noise figure measurements
with a mixer as the DUT
converting device can be used as
either the DUT or as part of the
measurement system. For this
demonstration we will use
a variable system LO, fixed
IF and frequency conversion
in the DUT. Since there is no
filtering in our measurement
system, we will insert a known
3 dB loss before the DUT. This
will make our measurement
more accurate. The NFA only
calibrates at one frequency (the
IF frequency), and then sweeps
the LO to make the measurement, producing the user-set
number of measurement points
(in this case 11, the default
number) across the swept frequency span from 3.5 GHz to
4.2 GHz.
Objective:
• Show the ability of the
NFA to make noise figure
measurements with a mixer
as a DUT
There are three primary hard
keys involved in the setting up
of a mixer noise figure measurement. These are Meas. Mode,
Mode Setup and System. These
hard keys can be found in the
MEASURE and SYSTEM key
groups.
Please take care to calibrate
with only the noise source
connected.
There are five different modes
in which a frequency down-
GPIB Cable
NFA Series Noise
Figure Analyzer
SNS Series
Noise Source
SSB
Filter
11730A
cable
Front
Output
(Signal generator and its associated cabling
and connectors not supplied in demo kit)
Mini Circuits Mixer
Figure 24. is a post-calibration connection diagram.
40
Signal Generator
Instructions
Keystrokes
Change Measurement Mode
[Measurement Mode] DUT
{Down-converter} LO mode {variable}
Change the Measurement Mode setup
to enable measurement of a device
containing frequency down-conversion.
[Mode Setup] Navigate around table using
the tab keys followed by the keypad and
then [Enter] to Modify.
{IF Frequency} 40 MHz enter by keypad [Enter]
{Sideband} {DSB}
{LO control} toggle to On
{External LO power level} enter 9 {dBm}
by keypad and then [Enter]
Enter the loss compensation values
as in Section 7
Loss before DUT is -3 dB at a temp of 290˚K
View the output measurement
[Format] {Table}
Change the system LO specifications
[System] {LO GPIB} control toggle to
On [Prev] External LO then enter LO min
frequency/max frequency (dependant
upon LO) system will sweep from min to max
and then convert to fixed IF
Calibrate system (as per Figure 7)
[Frequency points] Leave as default,
start frequency 3.5 GHz
Stop frequency 4.2 GHz. Will calibrate at
only 40 MHz [Calibrate] [Calibrate]
Connect up the Mini-Circuits mixer DUT
and measurement system as shown
in Figure 20.
NO Keystrokes relevant
41
Advanced noise
figure measurements
(continued)
Section 12.
Noise figure measurements
with a mixer as part of the
measurement system
In this section we shall be
covering the initial setup of
noise figure measurements
using a mixer as part of the
measurement system. The
setup is shown in Figure 25.
This section of the demo guide
is not as detailed as the previous sections. The demo kit does
not provide the DUT for these
measurements. Therefore, the
following is a simplified example
of how to set up this type of
measurement.
To set up a measurement using
a DUT that has an operating
frequency above the pass band
of the 3.0 GHz NFA, we use a
mixer. The LO and mixer have
to be calibrated out of the
measurement system because
they add noise and a loss to the
measurement. Together, these
two factors are considered a
second stage noise contribution.
To make an SSB (Single Side
Band) measurement additional
filtering may be required. This
additional filtering and the noise
figure/loss associated with it
should also be removed from the
measurement system during calibration. This can be done using
loss compensation modes (see
previous sections).
A filter is required in system
downconverter, fixed LO, and
variable IF mode since only
LSB (Lower Side Band) or USB
(Upper Side Band) can be
selected. DSB (Double Side
Band) can only be selected
with a fixed IF and variable
LO. DSB does not necessarily
require a filter.
Mixer as the part of the
measurement system
GPIB cable
NFA series noise
figure analyzer
Signal generator
Front
Output
DUT
Filter
Noise source
CAL
+ 28 Volt drive
Figure 25
42
Mixer
(Signal generator and its associated
cabling and connectors not supplied
in demo kit)
GPIB Cable
NFA Series Noise
Figure Analyzer
SNS Series
Noise Source
Signal Generator
Front
Output
(Signal generator and its associated cabling
and connectors not supplied in demo kit)
11730A
cable
Mini Circuits Mixer
Figure 26
Instructions
Keystrokes
Turn on system downconverter and select
a variable local oscillator which will be
controlled by the NFA.
[Meas Mode] [⇒|] to highlight system
downconverter {On} then select LO Mode
using [⇒|], then {variable}
The DUT itself contains no frequency
conversion, this is the default setting
on the NFA.
Change the Measurement Mode setup to
enable the measurement system to have
control of its frequency downconversion.
[Mode Setup] Navigate around table using [⇒|]
followed by the softkey to modify.
{IF Frequency} 40 enter by keypad and {MHz}
Sideband {DSB}
LO control {On}
Sideband {DSB}
{External LO power level} enter 7
by keypad and then [dBm]
Enable the system LO control
[System] {LO GPIB} LO GPIB control
{On} [Prev] {External LO} {Min Freq}
dependant upon choice of Local Oscillator
{Max Freq} also dependant upon
local oscillator
Change the system frequency parameters
[Frequency/Points] {Start Frequency}
3.5 by keypad then {GHz} {Stop Frequency}
5.0 by keypad then {GHz}
Calibrate system (connect up as per diagram) [Calibrate] [Calibrate]
Plug in the DUT to make the measurement
43
None
Advanced noise
figure measurements
(continued)
Section 13.
Printer setup/landscape/portrait
Landscape/portrait printing
When using this family of noise
figure analyzers with HP PCL5
printers, you can enjoy the
option of landscape printing.
This feature offers great flexibility in displaying and recording selected signal readings.
The NFA is factory preset for
automatic configuration of
printers. Portrait is also the
standard setting for layout, but
this can be changed if the user
wishes to use a PCL5 printer
for landscape printing.
Instructions
Keystrokes
Connect printer to the parallel port
via an IEEE-1284 compliant cable
None
Set instrument up for printing.
[Print Setup] {Orientation} {Landscape}
or {Portrait}
Select whether your printout is to
be in color or black & white
[Colour] Toggle to On or Off
Print screen.
[Print] if there is a printer hooked
up to the instrument.
Figure 27
44
Advanced noise
figure measurements
(continued)
Section 14 .
Help mode help
When using the NFA series of
noise figure analyzers, answers
to feature and function questions are only a button press
away. The built-in Help feature
provides you with on-screen
explanations of analyzer functions, including the SCPI remote
programming commands.
Instructions
Keystrokes
Turn Help on for a particular function
[Help] Then press the key you would
like to know more about its SCPI
command and function
Turn Help off.
Press any key to remove the help
screen from view.
45
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© Agilent Technologies, Inc. 2002
Printed in the USA March 29, 2002
5980-2028E
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