Keysight
N2830/1/2A and N7000/1/2/3A
InfiniiMax III+ Probes
User’s Guide
Notices
CAUTION
WARNING
© Keysight Technologies, Inc. 2016, 2017
No part of this manual may be reproduced in
any form or by any means (including electronic storage and retrieval or translation
into a foreign language) without prior agreement and written consent from Keysight
Technologies, Inc. as governed by United
States and international copyright laws.
Manual Part Number
N2830-97011
Edition
Eleventh Edition, December 2017
Published by:
Keysight Technologies, Inc.
1400 Fountaingrove Parkway
Santa Rosa, CA 95403 USA
Warranty
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Safety Notices
A CAUTION notice denotes a hazard.
It calls attention to an operating
procedure, practice, or the like that,
if not correctly performed or
adhered to, could result in damage
to the product or loss of important
data. Do not proceed beyond a CAU-
TION notice until the indicated conditions are fully understood and
met.
A WARNING notice denotes a hazard. It calls attention to an operating procedure, practice, or the like
that, if not correctly performed or
adhered to, could result in personal
injury or death. Do not proceed
beyond a WARNING notice until the
indicated conditions are fully
understood and met.
Contents
1 Using InfiniiMax III+ Series Probes 5
2 Using InfiniiMax III+ Probe Heads 39
Inspecting the Probe and Its Accessories 6
Introduction 9
Compatible Oscilloscopes 15
To Avoid Damaging the Probe 16
To Ensure Maximum Measurement Accuracy 21
To Use InfiniiMode 22
To Probe Ungrounded Devices 25
To Probe Single-Ended Signals with a Differential Head 26
To Measure Small Signals on a Large DC Level 27
Slew Rate Requirements for Different Technologies 30
Available Accessories 32
Safety Information 34
Service 37
Recommended Configurations at a Glance 40
N5444A InfiniiMax III 2.92 mm/3.5 mm/SMA Probe Head 42
N5439A InfiniiMax III ZIF Probe Head 45
N5445A InfiniiMax III Differential Browser Probe Head 51
N5441A InfiniiMax III Solder-In Head 57
N2836A InfiniiMode Solder-In Head 60
N2848A QuickTip InfiniiMode Probe Head 65
N2835A InfiniiMax III+ Differential Connectivity Kit and Accessories 69
Strain Relieving the Probe Heads 71
Soldering Tips 73
3 Maintaining Probe Heads 75
Replacing Axial Resistor Tips 76
Replacing N5441A Probe Head Wires 80
4 Calibration / Deskew Procedure 85
Procedure 86
3
5 Specifications and Characteristics 93
N2830/1/2A Probe Amplifier Specifications and Characteristics 94
N2830/1/2A Probe Head Characteristics 96
N7000/1/2/3A Probe Amplifier Specifications and Characteristics 97
N7000/1/2/3A Probe Head Characteristics 99
Environmental 100
Safety and Regulatory Information 101
Probe Dimensions 102
Probe Heads Dimensions 103
6Performance Plots 107
InfiniiMax III+ Probe System Responses 108
N2848A QuickTip Head with N2849A QuickTip 111
N2836A Solder-In Probe Head (Flat Orientation) 112
7 Performance Verification for N2830A-Series Probes 115
Bandwidth Performance Verification 116
DC Input Resistance Performance Verification 133
Performance Test Record 135
8 Performance Verification for N7000-Series Probes 137
Bandwidth Performance Verification 138
DC Input Resistance Performance Verification 147
Performance Test Record 149
9SPICE Models 151
N2848A QuickTip Head with N2849A QuickTip Tip 152
N5439A ZIF Probe Head with N5440A ZIF Tip 153
N5439A ZIF Probe Head with N2838A ZIF Tip 154
N2836A 26 GHz Solder-In Probe Heads 155
N5441A 16 GHz Solder-In Probe Head 156
N5445A Browser Probe Head 157
N5444A SMA Probe Head 159
4 InfiniiMax III+ Series Probes User’s Guide
Keysight InfiniiMax III+ Series Probes
User’s Guide
1 Using InfiniiMax III+ Series
Probes
Inspecting the Probe and Its Accessories 6
Introduction 9
Compatible Oscilloscopes 15
To Avoid Damaging the Probe 16
To Ensure Maximum Measurement Accuracy 21
To Use InfiniiMode 22
To Probe Ungrounded Devices 25
To Probe Single-Ended Signals with a Differential Head 26
To Measure Small Signals on a Large DC Level 27
Slew Rate Requirements for Different Technologies 30
Available Accessories 32
Safety Information 34
Service 37
This user’s guide covers the N2830/1/2A and N7000/1/2/3A InfiniiMax III+ series
differential probes that are shown in Figure 1.
Figure 1 InfiniiMax III+ Series Probes
5
1 Using InfiniiMax III+ Series Probes
Inspecting the Probe and Its Accessories
The N2830/1/2A and N7000/1/2/3A InfiniiMax III+ probes are shipped with a case,
calibration information, probe handling guide, and probe information card that are
shown in Figure 2 on page 7 or Figure 3 on page 8. Most, but not all, of the
shipped items are shown in these figures. After opening the case, lift out the foam
cutout and flip the cutout over to reveal an calibration envelope and a handling
guide.
When you receive your probe, check the following items:
• Inspect the shipping container for damage.
Keep the damaged shipping container or cushioning material until the contents of the
shipment have been checked for completeness and the probe has been checked
mechanically and electrically.
• Check the accessories.
• If the contents are incomplete or damaged, notify your Keysight Technologies
Sales Office.
• Inspect the probe. If there is mechanical damage or defect, or if the probe does
not operate properly or pass calibration tests, notify your Keysight Technologies
Sales Office.
If the shipping container is damaged, or the cushioning materials show signs of
stress, notify the carrier as well as your Keysight Technologies Sales Office. Keep
the shipping materials for the carrier’s inspection. The Keysight Technologies
office will arrange for repair or replacement at Keysight Technologies’ option
without waiting for claim settlement.
6 InfiniiMax III+ Series Probes User’s Guide
Using InfiniiMax III+ Series Probes 1
Figure 2 N2830A-Series Probe and Accessories in Supplied Case
InfiniiMax III+ Series Probes User’s Guide 7
1 Using InfiniiMax III+ Series Probes
Figure 3 N7000A-Series Probe and Accessories in Supplied Case
8 InfiniiMax III+ Series Probes User’s Guide
Introduction
WARNING
CAUTION
Using InfiniiMax III+ Series Probes 1
The InfiniiMax III and III+ Probing System Family Diagram, Figure 4 on page 10,
shows compatible oscilloscopes, probes, and probe heads. The
connect to the oscilloscope using a precision-BNC connection (AutoProbe 1).
N7000/1/2/3A probes connect to the oscilloscope using a 3.5 mm connection (AutoProbe
2).
Figure 5 on page 11 and Figure 6 on page 12 identify most of the probe parts.
N2830/1/2A probes
The
Table 1 Probe Bandwidths
Probe Bandwidth Probe Bandwidth
N2832A 13 GHz N7003A 20 GHz
N2831A 8 GHz N7002A 16 GHz
N2830A 4 GHz N7001A 13 GHz
Both the
when using the N2848A QuickTip probe head, N2836A Solder-in head or N5444A
2.92 mm/SMA head. InfiniiMode allows you to switch between differential,
single-ended, and common mode measurements without needing to change or
reconnect the probe or probe leads. Switching measurements is accomplished
using the oscilloscope’s probe configuration dialog box. For more information,
refer to “To Use InfiniiMode" on page 22.
Before using the probe, refer to “Safety Information" on page 34.
Probe heads
AutoProbe 1 (Precision BNC)
Scope Connection
N7000A 8 GHz
InfiniiMax III+ N2830/1/2A and N7000/1/2/3A probes support InfiniiMode
AutoProbe 2 (3.5 mm)
Scope Connection
Before you can use the probe, you must connect one of the available probe heads
that are shown in Figure 4 on page 10 and documented in Chapter 2, “Using
InfiniiMax III+ Probe Heads". These probe heads are also compatible with the
InfiniiMax III N2800A-series probes.
Before using the probes, refer to “To Avoid Damaging the Probe" on page 16.
Differential probe heads offer easy measurement of differential signals and greatly
improve the measurement of single-ended signals. Single-ended probe heads
offer extremely small size for probing single-ended signals in confined spaces.
InfiniiMax III+ Series Probes User’s Guide 9
1 Using InfiniiMax III+ Series Probes
Figure 4 InfiniiMax III and III+ Family Diagram with Compatible Scopes and Probe Heads
(not to scale)
10 InfiniiMax III+ Series Probes User’s Guide
Using InfiniiMax III+ Series Probes 1
Figure 5 N2830/1/2A Probes
InfiniiMax III+ Series Probes User’s Guide 11
1 Using InfiniiMax III+ Series Probes
Figure 6 N7000/1/2/3A Probes
12 InfiniiMax III+ Series Probes User’s Guide
AutoProbe Interface Connectors
Figure 7 and Figure 8 show the AutoProbe interface connectors that connect the
probes to the oscilloscope. The N2830/1/2A probes use the AutoProbe I interface
which connects to precision BNC oscilloscope channel inputs. It is compatible with
Infiniium oscilloscopes such as the 90000A and S-series. Of course, the probe
model must be also supported by the oscilloscope software.
The N7000/1/2/3A probes use the AutoProbe II 3.5 mm interface, which is
compatible with 90000 Q/V/X/Z-series oscilloscopes without the use of an
adapter
Using InfiniiMax III+ Series Probes 1
Figure 7 N2830/1/2A’s AutoProbe I Interface Connector
Figure 8 N7000/1/2/3A’s AutoProbe II Interface Connector
InfiniiMax III+ Series Probes User’s Guide 13
1 Using InfiniiMax III+ Series Probes
WARNING
Voltage Limits
The N2830/1/2A and N7000/1/2/3A probes are designed for Measurement
Category I (CAT I). Measurement Category I is for measurements performed on
circuits not directly connected to a mains supply. Observe the following voltage
limits:
Maximum AC at probe tips: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5V
Maximum DC at probe tips: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .±18V
Always observe the ESD, temperature, maximum voltage, and maximum terminal
voltages listed on the probe labels.
N7000/1/2/3A probe buttons
Press the Menu button to bring up the oscilloscope’s Probe dialog box.
When using the N5445A browser head, press the Light button to turn on and off
the browser’s LED headlight. Pressing and holding this button will ramp the
intensity of the LED headlights so that you can adjust the brightness to
accommodate different lighting or glare conditions.
rms
Figure 9 Buttons on 7000/1/2/3A Probe
Cleaning the probe
If the probe requires cleaning, disconnect it from the oscilloscope and clean it with
a soft cloth dampened with a mild soap and water solution. Make sure the probe is
completely dry before reconnecting it to the oscilloscope.
Channel identification rings
When multiple probes are connected to the oscilloscope, use the channel
identification rings to associate the channel inputs with each probe. Place one
colored ring near the probe’s channel connector and place an identical color ring
near the probe head.
14 InfiniiMax III+ Series Probes User’s Guide
Compatible Oscilloscopes
The N2830/1/2A probe’s precision BNC AutoProbe I interface connects directly to
S-series and 90000A oscilloscopes. Use an N5442A adapter to connect to series
90000 Q, V, X, and Z-series Infiniium oscilloscopes. Use an N1022B adapter to
connect to the 86100D oscilloscope.
The N7000/1/2/3A probe’s AutoProbe II interface connects directly to series
90000 Q, V, X, and Z-series Infiniium oscilloscopes. Use an N5477A adapter to
connect to the 86100D oscilloscope.
The N2830/1/2A and N7000/1/2/3A probes are not compatible with Infiniium
9000 Series, InfiniiVision and any old generation Keysight, Agilent, or HP
oscilloscopes.
Table 2 N2830A-Series Probes and Compatible Infiniium Oscilloscopes
Oscilloscope Adapter Required Minimum Required Firmware
Using InfiniiMax III+ Series Probes 1
Version
90000 Q, V, X, and Z-Series N5442A 5.00
90000A Series none 5.00
S-Series none 5.00
86100C/D Series N1022A/B —
Table 3 N7000A-Series Probes and Compatible Infiniium Oscilloscopes
Oscilloscope Adapter Required Minimum Required Firmware
90000 Q, V, X, Z-Series none 5.50
86100C/D Series N5477A —
Is your oscilloscope software up-to-date?
Keysight periodically releases software updates to support your probe, fix known
defects, and incorporate product enhancements. To download the latest firmware,
go to www.Keysight.com and search for your oscilloscope’s model number. Click
on the “Drivers, Firmware & Software” tab under the Technical Support link.
Version
86100C/D sampling oscilloscope
The probes can be used with the 86100C/D sampling scope with degraded
performance, depending on the probe head used. Use only in differential 1x mode
(10:1 attenuation). For N2830/1/2A probes, use the N1022B adapter. For
N7000/1/2/3A probes, use the N5477A adapter.
InfiniiMax III+ Series Probes User’s Guide 15
1 Using InfiniiMax III+ Series Probes
CAUTION
CAUTION
CAUTION
CAUTION
CAUTION
CAUTION
To Avoid Damaging the Probe
In this section, you’ll learn to properly handle your probes to prevent damage and
maintain high performance. For more safe-handling information, go to
http://www.keysight.com/find/esd-best-practices-demo,.
Electrostatic discharge (ESD) can quickly and imperceptibly damage or destroy
high-performance probes, resulting in costly repairs. Always wear a wrist strap when
handling probe components.
Probes are sensitive devices and should be treated with care. Do not bend or kink the
probe amplifier cable. Do not drop heavy objects on the probe, drop the probe from
large heights, spill liquids on the probe, etc. Any of these examples can significantly
degrade the performance of the probe.
When storing the probe, it is best to coil the cable in a large radius and avoid a net
twist in the cable during the process. This can be done in a similar manner to how
garden hoses or extension cords are typically coiled.
InfiniiMax I and II probe heads cannot be used with Infiniimax III+ probe amplifiers and
InfiniiMax III+ probe heads cannot be used with InfiniiMax I and II amplifiers.
Never allow the probe head to be connected to the probe amplifer, if the probe
amplifier is not connected to the oscilloscope channel.
Always disconnect an N2836A or N5441A solder-in probe head from the probe
amplifier before unsoldering, moving to a new position, and resoldering the head.
Using a static-safe work station
InfiniiMax probes and accessories are ESD sensitive devices and should be treated
with care. Before using or handling the probe or accessories, always wear a
grounded ESD wrist strap and ensure that cables and probe heads are discharged
before being connected.
All work, including connecting probe amplifiers to the oscilloscope, should be
performed at a static-safe work station as shown in Figure 10.
16 InfiniiMax III+ Series Probes User’s Guide
Using InfiniiMax III+ Series Probes 1
Figure 10 Static-Safe Work Station
Many scopes including Keysight's 90000X or V series have a front-panel ground
socket. You can plug the wrist strap into the ground socket as seen in the following
picture.
Figure 11 Wrist Strap Connected to Oscilloscope Ground Socket
The static-safe work station shown in Figure 10 uses two types of ESD protection:
• Conductive table-mat and wrist-strap combination.
• Conductive floor-mat and heel-strap combination.
InfiniiMax III+ Series Probes User’s Guide 17
1 Using InfiniiMax III+ Series Probes
WARNING
CAUTION
CAUTION
CAUTION
Both types, when used together, provide a significant level of ESD protection. Of
the two, only the table-mat and wrist-strap combination provides adequate ESD
protection when used alone. To ensure user safety, the static-safe accessories
must provide at least 1 MW of isolation from ground. Purchase acceptable ESD
accessories from your local supplier.
These techniques for a static-safe work station should not be used when working on
circuitry with a voltage potential greater than 500 volts.
Safely connecting the probe to an oscilloscope
To protect against ESD damage, always use the four steps shown in Figure 12 on
page 19 when connecting your probe to the oscilloscope.
When connecting a probe head to a probe amplifier, push straight in. When
disconnecting a probe head from an amplifier, pull the probe head connectors straight
out of the sockets. Never bend the probe head in order to pry it loose from the
amplifier. Also, do not wiggle the probe head up and down or twist it to remove the
connectors from the sockets. This can damage the pins in the amplifier or the probe
head itself.
Probing the DUT
When making your measurements, you’ll often need to probe different locations on
the DUT. You can safely move any of the following three probe heads without
having to first break the amplifier-to-head connection:
• N5445A differential browser head
• N5439A ZIF head,
• N5444A 2.92 mm/3.5 mm/SMA head.
• N2848A QuickTip InfiniiMode head.
The only exception is when the DUT is not grounded to the oscilloscope via the AC
mains ground. In this case, connect the DUT ground to the oscilloscope ground
before moving the probe. An example of a device having a floating ground would
be a battery-powered DUT.
When probing with an N2836A and N5441A, always disconnect the probe head from
the amplifier before unsoldering, moving to a new position, and resoldering the head.
This is because some soldering-iron tips can hold a charge which can damage the
probe amplifier.
When probing with an N2848A, always disconnect the probe head from probe tip
before unsoldering, moving to a new position, and resoldering the tip. This is because
some soldering-iron tips can hold a charge which can damage the probe amplifier.
18 InfiniiMax III+ Series Probes User’s Guide
Using InfiniiMax III+ Series Probes 1
Figure 12 Connecting the Probe to the Oscilloscope
Safely disconnecting the probe from an oscilloscope
Always disconnect the probe head from the probe amplifier before:
• disconnecting the probe amplifier from the oscilloscope.
• switching the probe amplifier from one oscilloscope channel to another.
InfiniiMax III+ Series Probes User’s Guide 19
1 Using InfiniiMax III+ Series Probes
CAUTION
Never allow the probe head to be connected to the probe amplifier, if the probe
amplifier is not connected to the oscilloscope channel.
Figure 13 Probe Improperly Disconnected from Oscilloscope while Probe Head is Connected
to the Probe Amplifier
20 InfiniiMax III+ Series Probes User’s Guide
To Ensure Maximum Measurement Accuracy
To increase measurement accuracy, use the oscilloscope’s Select Probe Head dialog
box to indicate the type of probe head that is attached to the probe amplifier.
Making this selection allows the oscilloscope to apply the proper type of correction
filter (S parameter) for your measurement case. The correction filter increases
accuracy by flattening the magnitude and phase response of the probe. The
following two sources of S parameters are automatically used for the filter:
• S parameters of the InfiniiMax III+ probe amplifier. These S parameters are
unique to and stored on the probe amplifier.
• S parameters of the specific probe-head model. For example, the N2836A: DF
Solder-In (Vertical) selection applies S parameters for the N2836A head held in a
vertical position (perpendicular to the surface of the DUT).
To disp l ay t he dia log b ox, cl i ck Probes > Channel Setup Menu.
Using InfiniiMax III+ Series Probes 1
Figure 14 Select Probe Head Dialog Box
InfiniiMax III+ Series Probes User’s Guide 21
1 Using InfiniiMax III+ Series Probes
NOTE
NOTE
To Use InfiniiMode
InfiniiMode allows you to switch between differential, single-ended, and common
mode measurements without needing to change or reconnect the probe or probe
leads. Switching measurements is accomplished using the oscilloscope’s probe
configuration dialog box.
InfiniiMode is available when using InfiniiMax III+ N2830/1/2A and N7000/1/2/3A probes.
InfiniiMode is not available when using InfiniiMax I, II, or III probe amplifiers.
The N2848A QuickTip, N2836A Solder-In head, and N5444A SMA head are
InfiniiMode compatible.
The following table shows, depending on the probe tip and InfiniiMode setting,
which signal types can be measured.
Table 4 Supported InfiniiMode Measurements by Probe Tip
InfiniiMode
Setting
Differential Browser (full BW)
Single-Ended Browser (not supported) Browser (not supported)
Common-Mode Browser (not supported) Browser (not supported)
* Full bandwidth obtained by touching one tip to ground.
Signal Being Measured
Single-Ended Differential
*
Solder-In (lower BW) Solder-In (lower BW)
QuickTip (lower BW) QuickTip (lower BW)
Solder-In Solder-In
QuickTip QuickTip
Solder-In Solder-In
QuickTip QuickTip
Browser (full BW)
Because the N5445A browser tip has two leads instead of three, it is not InfiniiMode
compatible. However, you can still use the browser tip to measure single-ended signals by
selecting differential mode and touching one tip to ground.
Making InfiniiMode connections
When probing a differential or common mode signal, connect the probe tips as
shown in Figure 15. The positive (+) and negative (–) leads can be reversed by
swapping the connections at the probe amplifier.
22 InfiniiMax III+ Series Probes User’s Guide
Using InfiniiMax III+ Series Probes 1
NOTE
V
+lead
V
lead–
– 4V 1V– 3V==
V
+lead
V
lead–
+
2
----------------------------
4V 1V+
2
---------------2.5V==
V
+lead
gnd– 4V 0V– 4V==
V
lead–
gnd– 1V 0V– 1V==
Figure 15 Example InfiniiMode Probe Circuit Connections
Soldering the ground wires is not required when making differential or single-ended (+ or –
leads) measurements.
The following measurements can be made without reconnecting the probe tips.
These equations use the voltages shown in Figure 15.
Differential Measurement
Common Mode Measurement
Single-Ended Measurement with +Lead
Single-Ended Measurement with –Lead
InfiniiMax III+ Series Probes User’s Guide 23
1 Using InfiniiMax III+ Series Probes
Selecting the InfiniiMode mode
With the probe connected to an S-series, 90000 series, 90000 X, Q, Z, or V-series
Infiniium oscilloscope, perform the following steps:
1 Click Setup > Probe Configuration to open the Probe Configuration Setup dialog box
shown in Figure 16.
2 In the dialog box, click the Probe Amp block to open the Probe Amplifier dialog
box.
3 Select the InfiniiMode measurement mode: Differential, Single-Ended A,
Single-Ended B, or Common Mode. The default setting is Differential.
Figure 16 Probe Configuration Dialog Box and Probe Amplifier Dialog Box
24 InfiniiMax III+ Series Probes User’s Guide
To Probe Ungrounded Devices
NOTE
If the DUT is not grounded to the oscilloscope via the AC mains ground, connect
the DUT ground to the oscilloscope ground. An example of a floating ground is a
battery-powered device.
Without the ground connection, the common mode voltage is not guaranteed to
be within the common mode range of the probe amplifiers.
Failure to connect the ground may result in the display of inaccurate waveforms.
Using InfiniiMax III+ Series Probes 1
Figure 17 Grounding the DUT to an S-Series Oscilloscope
InfiniiMax III+ Series Probes User’s Guide 25
1 Using InfiniiMax III+ Series Probes
To Probe Single-Ended Signals with a Differential Head
Using a differential probe head rather than a single-ended probe head to probe
single-ended signals results in the advantages of higher bandwidth and increased
accuracy. Also no offset range is sacrificed when using a differential probe head,
as any supplied offset is applied only to the probe head’s plus side. To learn more
about applying a DC offset when probing, refer to “To Measure Small Signals on a
Large DC Level" on page 27.
If possible, orient the probe head vertically as shown in Figure 18. Laying the
probe head flat over a single-ended signal will cause coupling to the tip that can
degrade the performance. Notice that the head’s “–” lead is connected to ground.
Figure 18 Connecting a Differential Head to a Single-Ended Signal
26 InfiniiMax III+ Series Probes User’s Guide
To Measure Small Signals on a Large DC Level
Measuring small AC signals riding on top of a large DC can be challenging. By
subtracting out most or all of the DC component, the signal can be positioned to
better utilize the input’s available dynamic range. This is accomplished by applying
an offset by either the probe or oscilloscope channel. Scope channel offset is
applied when viewing differential signals. Probe offset is applied when viewing
single-ended signals.
Normal Offset Behavior
Figure 19 shows Normal selected in the Probe Offset dialog box. When probing
differential signals Normal allows you to apply probe offset using the oscilloscope’s
front-panel vertical offset controls.
Using InfiniiMax III+ Series Probes 1
Figure 19 Probe Offset Dialog Box (Normal Setting)
Probe Offset Behavior
When Probe is selected as shown in Figure 20 on page 28, the InfiniiMax III/III+
probe provides a very large offset range (up to ±16V) for probing single-ended
signals and a large common-mode range for probing differential signals. Use this
offset range to subtract most or all of the DC component of the input signal so
that the signal can better utilize the dynamic range of the input. This is possible
due to the designs having summing nodes at the amplifier input. For information
InfiniiMax III+ Series Probes User’s Guide 27
1 Using InfiniiMax III+ Series Probes
on properly using probe offset to ensure that you can get the maximum
performance and dynamic range from the InfiniiMax probe, refer to Keysight
application note 5988-9264EN.
Figure 20 Probe Offset Dialog Box (Probe Setting)
Understanding how to properly use offset for your application can ensure that you
get the maximum performance and dynamic range from your probes. The unique
method of applying probe offset in InfiniiMax differential probes allows the full
benefits of differential probing for single-ended signals without sacrificing offset
range. Table 5 on page 29 lists the interactions between the signal type and the
different offsets.
28 InfiniiMax III+ Series Probes User’s Guide
Table 5 Signal Type and Available Offset Range
Signal Being Probed
Single Ended Differential
Using InfiniiMax III+ Series Probes 1
Probe Head Type Differential or
Single Ended Head
Offset Applied To Probe
(channel offset is set to 0V)
Offset Range ±16V
(with 450 ohm probe head)
Description The offset voltage is subtracted from the input signal
before the probe’s differential amplifier. Since this
subtraction is done before any active circuits, the
offset range is large.
Differential Probe Head. A differential probe can
make higher bandwidth and more accurate
measurements on single-ended signals than a
single-ended probe and this method of applying
offset to only the plus side of a differential probe
means that there is no sacrificing of offset range. All
of the InfiniiMax III+ heads are differential.
Single-Ended Probe Head. Single-ended probe tips
do not have a minus lead so nothing is plugged into
the probe amplifier’s “–” input. This is normal and
does not cause any problems.
Differential Head
Oscilloscope Channel
(probe offset is set to 0V)
±2.5V
Since the plus and minus sides of differential
signals have the same dc component, the dc
component is subtracted out and the probe’s
output by definition is centered around ground.
The channel offset allows the waveform seen
on screen to be moved as desired. The
allowable dc component in the plus and minus
signals is determined by the common mode
range of the probe.
Any voltage applied to the probe’s offset input
jack is not used and has no effect on the signal.
InfiniiMax III+ Series Probes User’s Guide 29
1 Using InfiniiMax III+ Series Probes
Slew Rate Requirements for Different Technologies
The following table shows the slew rates for several different technologies. The
maximum allowed input slew rate is 18 V/ns for single-ended signals and 30 V/ns
for differential signals. Table 6 shows that the maximum required slew rate for the
different technologies is much less that of the probe.
Table 6 Slew Rate Requirements
Name of Technology Differential
Signal
PCI Express (3GIO) YES 9.6 19.2 50 1.6
RapidIO Serial 3.125Gb YES 8.0 16.0 60 1.6
10GbE XAUI (4x3.125Gb) YES 8.0 16.0 60 1.6
1394b YES 8.0 16.0 60 1.6
Fibre Channel 2125 YES 8.0 16.0 75 1
Gigabit Ethernet 1000Base-CX YES 7.8 15.5 85 2.2
RapidIO 8/16 2Gb YES 7.2 14.4 50 1.2
Infiniband 2.5Gb YES 4.8 9.6 100 1.6
HyperTransport 1.6Gb YES 4.0 8.0 113 1.5
SATA (1.5Gb) YES 1.3 2.7 134 0.6
USB 2.0 YES 0.9 1.8 375 1.1
DDR 200/266/333 NO 7.2 n/a 300 3.6
PCI NO 4.3 n/a 500 3.6
Max
Single-Ended
Slew Rate
(V/ns)
*
Max
Differential
Slew Rate
(V/ns)
Driver Min Edge
Rate (20%-80%
†
ps)
Max Transmitter
Level (Diff V)
AGP-8X NO 3.1 n/a 137 0.7
* The probe specification is 18 V/ns
† The probe specification is 30 V/ns
30 InfiniiMax III+ Series Probes User’s Guide
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