Operator’s
Manual
AP033 Active
Differential Probe
AP033 Active Differential Probe
Operator’s Manual
May 2013
© 2013 Teledyne LeCroy, Inc. All rights reserved.
Unauthorized duplication of Teledyne LeCroy documentation materials other than for internal sales
and distribution purposes is strictly prohibited. However, clients are encouraged to distribute and
duplicate Teledyne LeCroy documentation for their own internal educational purposes.
WaveSurfer, WaveRunner, and Teledyne LeCroy are registered trademarks of Teledyne LeCroy, Inc.
Windows is a registered trademark of Microsoft Corporation. Other product or brand names are
trademarks or requested trademarks of their respective holders. Information in this publication
supersedes all earlier versions. Specifications are subject to change without notice.
Warranty
Teledyne LeCroy warrants this oscilloscope accessory for normal use and operation within
specification for a period of one year from the date of shipment. Spare parts, replacement parts and
repairs are warranted for 90 days.
In exercising its warranty, Teledyne LeCroy, at its option, will either repair or replace any assembly
returned within its warranty period to the Customer Service Department or an authorized service
center. However, this will be done only if the product is determined by Teledyne LeCroy’s
examination to be defective due to workmanship or materials, and the defect is not caused by
misuse, neglect, accident, abnormal conditions of operation, or damage resulting from attempted
repair or modifications by a non-authorized service facility.
The customer will be responsible for the transportation and insurance charges for the return of
products to the service facility. Teledyne LeCroy will return all products under warranty with
transportation charges prepaid.
This warranty replaces all other warranties, expressed or implied, including but not limited to any
implied warranty of merchantability, fitness or adequacy for any particular purposes or use.
Teledyne LeCroy shall not be liable for any special, incidental, or consequential damages, whether in
contract or otherwise.
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Operator’s Manual
Table of Contents
Safety Instructions............................................................................................... 1
Symbols .................................................................................................................. 1
Precautions............................................................................................................. 1
Operating Environment.......................................................................................... 2
Overview ............................................................................................................ 3
Description ............................................................................................................. 3
Applications ............................................................................................................ 3
Standard Accessories ............................................................................................. 4
Optional Accessories .............................................................................................. 4
Oscilloscope Software Compatibility...................................................................... 4
Specifications ...................................................................................................... 5
Operation ........................................................................................................... 8
Connecting the Probe to the Test Instrument ....................................................... 8
Connecting the Probe to the Test Circuit ............................................................... 8
Probe Input Loading ............................................................................................. 10
Grounding the Probe ............................................................................................ 10
Selecting the Proper Range .................................................................................. 11
Operation with Teledyne LeCroy Oscilloscopes ................................................... 12
Adding Offset........................................................................................................ 14
Autobalance ......................................................................................................... 15
Designing Test Fixtures for the AP033 Probe ....................................................... 16
Maintenance ..................................................................................................... 17
Cleaning ................................................................................................................ 17
Calibration Interval ............................................................................................... 17
Service Strategy .................................................................................................... 17
Troubleshooting ................................................................................................ 18
Returning a Probe ............................................................................................. 20
Available Accessories......................................................................................... 21
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AP033 Active Differential Probe
Matching Procedure for ÷10 Plugs ...................................................................... 22
Equipment Required.............................................................................................22
Procedure .............................................................................................................23
Performance Verification ................................................................................... 25
Test Equipment Required .....................................................................................25
Preliminary Procedure ..........................................................................................27
Procedure .............................................................................................................27
Adjustment Procedure ....................................................................................... 35
Introduction ..........................................................................................................35
Test Equipment Required .....................................................................................36
Preliminary Procedure ..........................................................................................38
Procedure .............................................................................................................39
Reference Information ....................................................................................... 48
Differential Mode and Common Mode ................................................................48
Differential Mode Range and Common Mode Range ..........................................48
Common Mode Rejection Ratio ...........................................................................49
Certifications ........................................................................................................50
Contact Teledyne LeCroy .................................................................................... 53
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Safety Instructions
This section contains instructions that must be observed to keep this oscilloscope accessory
operating in a correct and safe condition. You are required to follow generally accepted safety
procedures in addition to the precautions specified in this section. The overall safety of any system
incorporating this accessory is the responsibility of the assembler of the system.
Symbols
These symbols may appear on the probe body or in this manual to alert you to important safety
considerations.
HIGH VOLTAGE, risk of electric shock.
CAUTION of Potential damage to probe or instrument it is connected to, or
WARNING of potential bodily injury. Attend to the accompanying
information to protect against personal injury or damage. Do not proceed
until conditions are fully understood and met.
ELECTROSTATIC DISCHARGE (ESD) HAZARD. The probe is susceptible to
damage if anti-static measures are not taken.
DOUBLE INSULATION
PROTECTIVE (EARTH) TERMINAL
Precautions
To avoid personal injury, or damage to the probe or test instrument, comply with the following
safety precautions.
Use product only as specified.
Connect and disconnect properly. Connect probe to the measurement instrument before
connecting the test leads to a circuit/signal being tested.
Use only accessories compatible with the probe. Use only accessories that are rated for the
application. Ensure connections between probe input leads and probe accessories are secure
before connecting them to a voltage source.
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AP033 Active Differential Probe
Do not overload. To avoid electric shock, do not apply any potential that exceeds the maximum
rating of the probe and/or the probe accessory, whichever is less. Observe all terminal ratings of
the instrument before connecting the probe.
Be careful not to damage the insulation surface when making measurements.
Use only within operational environment listed. Do not use in wet or explosive atmospheres.
Keep product surfaces clean and dry. Use indoors only.
Handle with care. Probe accessory tips are sharp. They can puncture skin or cause other bodily
injury if not handled properly.
Keep fingers behind the finger guard of the probe accessories.
Do not operate with suspected failures. Before each use, inspect the probe and accessories for any
damage such as tears or other defects in the probe body, cable jacket, accessories, etc. If any part
is damaged, cease operation immediately and sequester the probe from inadvertent use.
Operating Environment
Only use the product within this operating environment:
Temperature: 0° to 50° C
Humidity: Maximum relative humidity 90 % for temperatures up to 31° C decreasing linearly to
50% relative humidity at 40° C
Altitude: Up to 10,000 ft (3,048 m)
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Overview
Description
The AP033 is a wide band differential active probe. The probe features low noise, low input
capacitance, high common mode rejection, and FET-buffered inputs in the probe head. User
selectable attenuation and offset give the probe flexibility to measure a large range of signal
amplitudes. Plug-on attenuator and AC coupling accessories further extend the application range.
Interconnect accessories included allow connection to surface mount and through-hole
components with minimal signal degradation. The input receptacles in the probe head are
compatible with standard 0.025 in. (0.635 mm) square pins. This provides a convenient low cost
method of creating device characterization test fixtures.
The probe is powered directly from a Teledyne LeCroy oscilloscope through the ProBus® interface.
The ProBus interface also allows local control of the probe through the oscilloscope user interface
and remote control through the interface buses, (GPIB, RS-232). The optional ADPPS power supply
allows the AP033 to be used with other instruments such as spectrum analyzers, network
analyzers, and oscilloscopes without ProBus interface.
Applications
The AP033 is ideal for acquiring high speed differential signals such as those found in disk drive
read channels, differential LAN, video, etc. It can also be used with spectrum analyzers to acquire
signals in some RF systems (for example, balanced IF mixers in hand held cellular telephones). The
high impedance characteristics of both inputs allow the probe to be used as a FET probe to make
single-ended measurements in digital systems without introducing a ground loop, as a conventional
FET probe would.
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AP033 Active Differential Probe
Standard Accessories
Hard Case
÷10 Plug-on Attenuator
Plug-on AC Coupler
Probe Connection Accessory Kit:
Flex Lead Set (1)
Mini Clip, 0.8 mm (3)
Mini Clip, 0.5 mm (2)
Ground Lead (1)
Offset Pins, Round (4)
Square Pin Header Strip (1)
Manual, AP033 Active Differential Probe Operator’s Manual
Optional Accessories
ADPPS Power Supply
Oscilloscope Software Compatibility
For full control functionality of the probe, Teledyne LeCroy LC series oscilloscopes must have
software version 8.1.0 or higher loaded; all X-Stream oscilloscopes are compatible. The software
version installed in a Teledyne LeCroy oscilloscope can be verified by pressing the SHOW STATUS
button on the front panel (where available), then selecting the System menu choice. The probe can
be used with earlier versions of software; however, probe offset can only be controlled through the
buttons on the probe body. Also, the scale factor will be displayed incorrectly in some modes.
For information on upgrading the software in your oscilloscope, see
teledynelecroy.com/support/softwaredownload, or contact your local Teledyne LeCroy
representative.
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Specifications
Nominal Characteristics
Nominal characteristics describe parameters and attributes that have are guaranteed by design,
but do not have associated tolerances.
Input Configuration:
True Differential (+ and – Inputs); with shield Ground connector.
Effective Gain1:
X1, X10, ÷10, ÷1002
Input coupling:
DC. AC Coupling obtained by installing AC Coupling Adapter.
Differential Mode Range:
(10X Gain):
±40 mV
±400 mV
±4 V
(÷1 Attenuation)
(÷10 Attenuation)
(÷100 Attenuation)
(1X Gain):
±400 mV
±4 V
±40 V
(÷1 Attenuation)
(÷10 Attenuation)
(÷100 Attenuation)
±4.2 V
±42 V
±42 V
(÷1 Attenuation)
(÷10 Attenuation)
(÷100 Attenuation)
Common Mode Range:
Maximum Input Voltage:
1
2
±42 V either input from ground
From combination of gain, internal and external attenuation.
Use external plug-on ÷10 attenuator for ÷100.
Warranted Electrical Characteristics
Warranted characteristics are parameters with guaranteed performance. Unless otherwise noted,
tests are provided in the Performance Verification Procedure for all warranted specifications.
LF Gain Accuracy:
2% into 50 Ωload3, measured at 1 kHz with 0 V offset
Common Mode Rejection Ratio4 (Probe head grounded, DC Coupled, ÷1 attenuation without
external attenuator):
70 Hz
≥ 3160:1
(70 dB)
1 MHz
≥ 1000:1
(60 dB)
250 MHz
≥ 5:1
(14 dB)
3
Output impedance 50 Ω, intended to drive 50 Ω. Add uncertainty of termination impedance to accuracy.
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AP033 Active Differential Probe
4
Teledyne LeCroy measures CMRR with a fixture that connects the probe tip ground to the signal source
ground. This method is necessary to obtain a reproducible CMRR measurement. Often, users leave the
probe tip ungrounded when measuring high frequency signals. Not grounding the probe tip can actually
improve CMRR by allowing some of the common mode signal to be impressed across the entire length of
the probe cable instead of from probe tip to probe ground. The CMRR improvement obtained without
grounding the probe tip depends on proximity to probe cable ground, and is therefore non-reproducible.
Teledyne LeCroy has chosen to use a reproducible method of measurement, rather than obtain a more
optimistic measurement.
Typical Electrical Characteristics
Typical characteristics are parameters with no guaranteed performance. Tests for typical
characteristics are not provided in the Performance Verification Procedure.
Bandwidth, probe only (-3 dB):
Risetime, probe only:
Residual Autobalance Offset (Ref.to input):
Differential Offset Range:
CMRR:
Input Resistance (each side to ground):
Input Capacitance (between inputs):
(each side to ground):
Noise (referred to input, 5 to 1000 MHz):
Output Impedance:
Harmonic Distortion (3rdorder distortion):
(3rd order intercept):
AC Coupling LF Cutoff (-3dB):
6
DC to 500 MHz
≤ 700 ps (÷10 Attenuation)
≤ 875 ps (÷1 Attenuation)
≤ 100 μV (÷1 Attenuation)
≤ 1.5 mV (÷10 Attenuation)
±400 mV (÷1 Attenuation)
± 4 V (÷10 Attenuation)
± 40 V (÷100 Attenuation)
See Figure 1.
1MΩ
< 1.6 pF (÷10 Attenuation)
< 3.1 pF (÷1 Attenuation)
6 nV/√Hz (÷1 Attenuation, 10X Gain)
10 nV/√Hz (÷1 Attenuation, 1X Gain)
60 nV/√Hz (÷10 Attenuation, 10X Gain)
115 nV/√Hz (÷10 Attenuation, 1X Gain)
50 Ω nominal, intended to drive 50 Ω
-52 dB below fundamental (200 mVp-p output at 100 MHz)
+15 dBm (at 100 MHz measured at output)
16 Hz
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Operator’s Manual
Figure 1, Typical CMRR Graphs
Temperature:
Input Connectors:
Power Requirements:
Control Housing:
Compatible with 0.025” (0.635 mm) square pins.
0.036” (0.91 mm) maximum diameter (for round pins)
Powered from oscilloscope through ProBus interface
or with ADPPS power supply.
Dimensions
Length: 3.625 in (9.2 cm)
Width: 1.50 in (3.8 cm)
Height: 1.00 in (2.5 cm)
Head:
Length: 4.0 in (10.1 cm) w/o Attenuator or AC Coupler
Width: 2.25 in (2.25 cm)
Height: 0.625 in (1.6 cm)
Cable:
Length: 42 in (106 cm)
Diameter: 0.275 in (7.0 mm)
Weight:
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General Characteristics
0° to 50° C Operating
-40° to 75° C Storage
Probe only: 6.4 oz (0.18 kg)
Shipping: 2 lbs, 8.4 oz (1.15 kg)
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AP033 Active Differential Probe
Operation
CAUTION: The input circuits in the AP033 incorporate components that protect the probe
from damage resulting from electrostatic discharge (ESD). Keep in mind that this is an active probe,
and it should be handled carefully to avoid damage. When using the AP033, you are advised to take
precautions against potential instrument damage due to ESD.
Connecting the Probe to the Test Instrument
When using the AP033 Active Differential Probe with a Teledyne LeCroy Oscilloscope equipped
with ProBus, attach the probe output connector to the oscilloscope input connector. The
oscilloscope will recognize the probe, set the oscilloscope input termination to 50Ω, and activate
the probe control functions in the user interface.
To use the AP033 Active Differential Probe with instrumentation not equipped with a ProBus
interface, it is necessary to use the ADPPS Power Supply. Attach the ADPPS connector to the probe
output connector. The output connector of the ADPPS is a standard male BNC that can be directly
connected to another instrument. If necessary, the output of the ADPPS can be interconnected
with a 50 Ω coaxial cable. To minimize the effect of skin loss, this cable should be 1 m or less in
length. The AP033 Active Differential Probe is designed to drive a 50 Ω load. The gain will be
uncalibrated if the output is not correctly terminated. If you are using the probe with an instrument
with a high input impedance, place a 50 instrument input before attaching the ADPPS..
Connecting the Probe to the Test Circuit
At the probe tip, two inputs and a ground connection are available for connecting the probe to a
circuit under test. For accurate measurements, both the + and – inputs must always be connected
to the test circuit. The ground connection is optional. Positive voltages applied to the + input
relative to the – input will deflect the oscilloscope trace toward the top of the screen.
Positive voltages applied to the + input relative to the – input will deflect the oscilloscope trace
toward the top of the screen.
To maintain the high performance capability of the probe in measurement applications, user care
in connecting the probe to the test circuit. Increasing the parasitic capacitance or inductance in the
input paths may introduce a “ring,” or slow the rise time of fast signals. To minimize these effects,
use the shortest length possible when connecting the probe to the circuit under test. Input leads
that form a large loop area (even shielded coaxial cables) will pick up any radiated magnetic field
that passes through the loop, and may induce noise in the probe inputs. Because this signal will
appear as a differential mode signal, the probe’s common mode rejection will not remove it. You
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can greatly reduce this effect by using short interconnection leads, and twisting them together to
minimize the loop area.
High common mode rejection requires precise matching of the relative gain or attenuation in the +
and – input signal paths. Mismatches in additional parasitic capacitance, inductance, delay, and a
source impedance difference between the + and – signal paths will lower the common mode
rejection ratio. Therefore, it is desirable to use the same length and type of wire and connectors for
both input connections. When possible, try to connect the inputs to points in the circuit with
approximately the same source impedance.
If AC coupling is desired, install the AC coupling accessory on the probe tip before connecting it to
the test circuit. The low-frequency cutoff (–3 dB point) of the AC coupler is approximately 16 Hz.
If the voltage in the test circuit requires more than ÷10 attentuation, add the external ÷10
attenuator to the probe tip. If using both the external attenuator and AC coupler, install the
attenuator on the probe tip first, then install the AC coupler on the attenuator input.
In addition to being compatible with the included lead set, the probe input connectors will mate
with standard 0.025 in. (0.635 mm) square pins in any rotational orientation. To avoid damaging
the input connectors, do not attempt to insert connectors or wire larger than 0.036 in. (0.91 mm) in
diameter. Avoid rotating square pins after they are inserted into the input connectors.
The included accessories simplify the task of connecting the probe to the test circuit:
Use the small (0.5 mm) mini clips with the flexible lead set when connecting to fine-pitch
surface mount IC leads.
Use the larger (0.8 mm) mini clips to connect to through-hole leaded components.
Use the offset round pins for hand-held probing applications. Reposition the pins by
rotating them to obtain the required spacing.
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AP033 Active Differential Probe
Probe Input Loading
Attaching any probe to a test circuit will add some loading. In most applications, the high
impedance of the AP033 Active Differential Probe inputs imparts an insignificant load to the test
circuit. However at very high frequencies, the capacitive reactance of the probe’s input capacitance
may load the circuit enough to affect measurement accuracy. The equivalent model of the probe
input circuits is shown below:
Figure 2, AP033 Equivalent Input Model
Grounding the Probe
The single lead along with one of the larger (0.8 mm) mini clips can be used to ground the probe to
the test circuit. Insert the pin end of the lead into the receptacle marked:
CAUTION: Do not use the attenuator encoding receptacle (unmarked socket near the – input)
to ground the probe. Connection to the encoding receptacle will not provide adequate grounding
and may result in an incorrect effective gain indication.
In many cases it is not necessary to ground the probe to the circuit under test. However, if the test
circuit is isolated from earth ground, it is usually necessary to connect the probe ground to a point
in the circuit. Grounding test circuits that are referenced to earth ground may improve the fidelity
of high frequency components in the waveforms. The potential for improvement with grounding
will vary depending on the common mode source impedance. However, connecting the probe
ground to a circuit that is referenced to earth ground can create a ground loop that may add noise
to low amplitude signals. The rejection of high frequency common mode signals is improved when
the probe head is ungrounded.
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The best recommendation for connecting or not connecting the probe ground is to try both
configurations and select the one that performs the best.
NOTE The AP033 Active Differential Probe transmits the measured signal differentially through the
probe cable. This essentially eliminates signal degradation from ground loop effects within the
probe. However, creating a ground loop may introduce signal distortions in the test circuit itself, or
in any coaxial cable between the ADPPS power supply and the test instrument.
Selecting the Proper Range
The AP033 has two independent controls that set the common mode range and equivalent
volts/division. The probe gain can be set to x1 or x10. The gain control (GAIN) only affects the
differential mode range of the probe. A separate input attenuation control (ATTEN) sets the probe
input attenuator to either ÷ or ÷10. See Figure 3.
Figure 3, AP033 Block Diagram
The attenuator is located at the probe input and, therefore, affects both the differential mode and
common mode ranges. (Refer to the Reference Section for definitions of Common Mode and
Differential Mode.) By using the plug-on attenuator, you can extend the attenuation range to ÷100.
The maximum ranges are given in Table 1.
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AP033 Active Differential Probe
Table 1, AP033 Dynamic ranges and input capacitance at different attenuator settings
÷1 Attenuation
÷10 Attenuation
÷100 Attenuation
•±4.2 V
•±42 V •
±42 V
•±400 mV •
±4 V •
±40 V
•±40 mV •
±400 mV •
±4 V
Input Capacitance, each side to Ground
6.0 pF
3.0 pF
1.9 pF
Input Capacitance each side to Ground
with AC Coupler
7.3 pF
4.3 pF
3.2 pF
Common Mode Range
Differential Mode Range with
x1 Gain*
Differential Mode Range with
x10 Gain*
*Offset moves the center point of this range.
When you are using a differential probe or amplifier, be careful not to exceed the common mode
range. Because the common mode signal is rejected by the probe, and not displayed, changes in
the amplitude of the common mode component are not apparent. Exceeding the common mode
range may introduce distortion into the AP033 output. To reduce the possibility of errors caused by
exceeding the common mode range, the probe monitors the input voltage. If the common mode
range is exceeded when the ÷ input attenuator is selected, the probe will automatically switch to
the ÷attenuator. If the voltage on either input exceeds 55 volts, both the ÷ and
÷attenuator lights will alternately flash to alert the user to the over-range condition. There are
two combinations which result in x1 effective gain. A ÷attenuation with x10 gain results in
higher common mode range and lower input capacitance, but it increases the noise referred to the
input. Conversely, ÷ attenuation with x1 gain reduces the noise at the expense of less common
mode range and greater input capacitance.
Circuitry in the probe decodes the effective gain of the probe based on the settings of the gain,
internal attenuation and the presence of the external attenuator. The resulting effective gain is
displayed on the probe front panel.
Operation with Teledyne LeCroy Oscilloscopes
When the AP033 probe is connected to a Teledyne LeCroy oscilloscope equipped with the ProBus
interface, the displayed scale factor and measurement values will be adjusted to account for the
effective gain of the probe.
When the AP033 probe is first connected to the oscilloscope, the following message will appear:
“WARNING: Probe offset buttons are locked”. This is to alert the user that offset control must be
made through the oscilloscope, rather than through the buttons located on the probe. It does not
indicate a failure in the probe or oscilloscope.
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With oscilloscope software versions 7.6.0 and higher, the probe gain, internal attenuation, and
offset can be conveniently controlled through the oscilloscope’s user interface. The common mode
range is also displayed. Manual control through the oscilloscope user interface can be found in the
COUPLING menu or the Channel dialog of the channel to which the probe is connected. The
appearance and functionality of the control menu has changed with incremental versions of the
oscilloscope software.
With software versions 8.1.0 and higher, there are two modes of gain control: Auto and Manual.
The oscilloscope defaults to Auto mode when the probe is first attached. In Auto mode, the
VOLTS/DIV knob controls the oscilloscope’s scale factor, AP033 gain, and AP033 attenuation to give
the full available dynamic range: 200 μV/div to 1 V/div (without external attenuator), or 2 mV/div
to 10 V/div (with external ÷attenuator installed). Some of the transitions in scale factor will
result in a change of the attenuation in the AP033 probe. The common mode range, input
capacitance, and noise level of the probe will change with the probe attenuator setting. For
Volts/Div settings which can be produced with more than one combination of probe gain and
attenuation settings, Auto mode selects the combination which results in greater common mode
range and lower input capacitance.
In some situations, you may wish to select probe settings optimized for the lowest noise
performance with lower common mode range. Likewise, you may require that the probe not
change input capacitance, noise, or common mode range as you change the VOLTS/DIV setting.
These requirements can be met by setting the probe to Manual gain control mode. When set to
Manual mode, the dynamic range of the VOLTS/DIV knob is limited to the scale factors that can be
obtained without changing the AP033 gain or attenuation. Thus in Manual gain control mode, only
the scale factor of the oscilloscope will be changed. In this mode, dedicated menu boxes are
displayed for Probe Attenuation and Probe Gain. (Refer to Figure 3). The available values that
appear in the Probe Atten menu box will change depending on the presence of the external
attenuator. When the external ÷10 attenuator is not installed, ÷10 and ÷1 will be displayed. With
the external ÷10 attenuator, only ÷100 will be displayed. In software versions 8.1.0 and higher, the
channel OFFSET knob will control the probe offset, rather than the offset at the oscilloscope input.
The OFFSET buttons on the probe body are disabled.
The Coupling Menu refers to the probe input. The common mode dynamic range (CMDR) for the
selected probe gain and attenuation settings are displayed in the Probe Attenuation menu In some
versions of software, the input capacitance from each input to ground is also displayed.
When using the AP033 with the ADPPS power supply on oscilloscopes without a ProBus interface,
use Table 2 to select the desired effective volts per division scaling.
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AP033 Active Differential Probe
Table 2, Recommended oscilloscope settings to obtain desired equivalent Volts/Division
Equivalent
Scale Factor
Oscilloscope
Scale Factor
AP033
Attenuation
AP033
Gain
Common
Mode
Range
Differential
Mode
Range
Maximum
Offset
Input
Noise
(nV/√Hz)
100 μV/Div
1 mV/Div
÷1
X10 •
±4.2 V •
±40 mV •
±400 mV
6
200 μV/Div
2 mV/Div
÷1
X10 •
±4.2 V •
±40 mV •
±400 mV
6
500 μV/Div
5 mV/Div
÷1
X10 •
±4.2 V •
±40 mV •
±400 mV
6
1 mV/Div
10 mV/Div
÷1
X10 •
±4.2 V •
±40 mV •
±400 mV
6
2 mV/Div
20 mV/Div
÷1
X10 •
±4.2 V •
±40 mV •
±400 mV
6
5 mV/Div
50 mV/Div
÷1
X10 •
±4.2 V •
±40 mV •
±400 mV
6
10 mV/Div
100 mV/Div
÷1
X10 •
±4.2 V •
±40 mV •
±400 mV
6
20 mV/Div
20 mV/Div
÷10
X10 •
±42 V •
±400 mV •
±4 V
60
50 mV/Div
50 mV/Div
÷10
X10 •
±42 V •
±400 mV •
±4 V
60
100 mV/Div
100 mV/Div
÷10
X10 •
±42 V •
±400 mV •
±4 V
60
200 mV/Div
20 mV/Div
÷10
X1 •
±42 V •
±4 V •
±4 V
115
500 mV/Div
50 mV/Div
÷10
X1 •
±42 V •
±4 V •
±4 V
115
1 V/Div
100 mV/Div
÷10
2 V/Div
5 V/Div
10 V/Div
20 mV/Div
50 mV/Div
100 mV/Div
X1 •
±42 V •
±4 V •
±4 V
115
÷100
1
X1 •
±42 V •
±40 V •
±40 V
1150
÷100
1
X1 •
±42 V •
±40 V •
±40 V
1150
÷100
1
X1 •
±42 V •
±40 V •
±40 V
1150
1÷100
attenuation obtained using the external ÷attenuator. The probe is automatically set to ÷internally when the
external attenuator is installed. The internal ÷ attenuator cannot be selected when the external ÷10 attenuator is installed.
Adding Offset
The AP033 has true differential offset capability. This allows you to remove a DC bias voltage from
the differential input signal while maintaining DC coupling. By using probe offset rather than the
“position” control on the oscilloscope, the full dynamic range of the probe remains centered
around the offset level.
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Figure 4, Effect of Differential Offset
When the AP033 is used with a Teledyne LeCroy oscilloscope equipped with a ProBus interface and
software versions 7.6.0 to 8.0.0, the probe offset must be controlled through either the Probe
Offset menu selection in the COUPLING screen, or the buttons on the probe body. The channel
OFFSET control does not change the probe offset and, therefore, should not be used.
When used with the ADPPS Power Supply on instruments that lack ProBus support, offset can be
controlled with the buttons on the front panel. The offset can be returned to zero at any time by
briefly pressing the ↑ and ↓ OFFSET buttons at the same time. Pressing and holding the ↑ and
↓ OFFSET buttons for more than two seconds will initiate an Autobalance cycle.
Autobalance
The AP033 incorporates an Autobalance function to remove the DC offset from the output.
Autobalance must be invoked by you. When power is first applied, the probe will return to the
internal values resulting from the last Autobalance cycle. For Autobalance to function properly, all
signals must be removed from the input.
After several minutes of warm up, or when the probe is exposed to a large shift in ambient
temperature, some DC offset drift may occur from thermal effects in the amplifier circuitry. To
initiate an Autobalance cycle, remove the probe from the test circuit and select AUTOBALANCE
from the oscilloscope’s COUPLING menu for the channel the probe is connected to. If the probe is
being used with the ADPPS power supply, remove the input signal, and push and hold both the
OFFSET buttons for two seconds. The AP033 output must be terminated into 50 Ω for successful
Autobalance.
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AP033 Active Differential Probe
Upon successful completion of the Autobalance cycle, all four of the EFFECTIVE GAIN indicators will
be briefly illuminated. If an input signal is present during auto balancing and the routine fails, the
EFFECTIVE GAIN indicators will not illuminate. The probe will then revert to the offset values that
resulted from the last successful completion of the Autobalance cycle. In many situations, this will
be adequate to make routine measurements.
Designing Test Fixtures for the AP033 Probe
Often it is desirable to connect the probe directly to user fabricated test fixtures, such as those
used for semiconductor characterization. To facilitate use with custom test fixtures, the input
receptacles of the AP033 probe are compatible with commercially available 0.025 in. (0.635 mm)
square pins. The receptacles do not require a specific rotational alignment for the square pin. The
dimensions listed below can be used as a layout guide for a test fixture circuit board. The
recommended insertion depth of the pins is 0.100 in. (2.5 mm) to 0.200 in. (5.0 mm).
Figure 5, Layout dimensions for test fixtures
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Maintenance
This probe is a high quality, precision instrument. To maintain accuracy and signal fidelity,
mechanical shock should be avoided, as well as damage to the cable through excessive bending.
To achieve the small 2.5 mm tip size, the input tip diameter is narrower than those in larger probes.
Avoid placing excessive force sideways on the tip. Should the tip become damaged, it may be
replaced. Other maintenance and component replacement should be referred to qualified
personnel.
Cleaning
The outside of the probe should cleaned with a soft cloth dampened with either deionized /
distilled water or isopropyl alcohol. Allow the surface to dry completely before returning the probe
to service. Never immerse the probe in any liquid.
Calibration Interval
To guarantee accurate performance, you should have the probe calibrated every 12 months. Avoid
exposing the probe to extreme mechanical shock and excessive bending of the cable because these
may alter the calibration.
Service Strategy
The AP033 circuits utilize fine pitch surface mount devices; it is, therefore, impractical to attempt
component-level repair in the field. Defective probes must be returned to a Teledyne LeCroy
service facility for diagnosis and exchange. A defective probe under warranty will be replaced with
a factory refurbished probe. A probe that is not under warranty can be exchanged for a factory
refurbished probe. A modest fee is charged for this service. The defective probe must be returned
in order to receive credit for the probe core.
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AP033 Active Differential Probe
Troubleshooting
If the probe is not operating properly the problem may be the way in which it is used. Before
assuming the probe is defective, perform the following troubleshooting procedures.
A. Trace Off Scale
This is typically caused by improper offset setting, or by an input signal that exceeds the probe
differential or common mode range.
1. Remove the input signal from the probe, return the offset to zero, and Autobalance the probe.
Does the trace return to approximately the center of the graticule? If not, proceed to step 7.
2. Set the oscilloscope calibrator to output a 100-mV 1-kHz square wave. Using the flex lead set,
connect the probe + input to the calibrator output signal, leave the – input open. Set the
oscilloscope to 50 mV/div and 500 s/div. Is the displayed waveform a 100-mV 1-kHz square
wave with the correct polarity?
3. Repeat step 2 with the – input connected to the calibrator and the + input left open. In this
case, the displayed waveform should be inverted.
4. Connect both the + input and – input to the calibrator output. Is the trace approximately a flat
line near zero volts?
5. If steps 1 to 4 give the correct results, the problem is likely a result of the input signal exceeding
the differential or common mode range.
6. Connect both the + input and – input to one of the two input signals. If the trace is off scale, the
input signal is probably exceeding the common mode range. Repeat with the other input signal.
7. Is a ProBus Power Supply Overload error message displayed? If so, remove all other ProBus
accessories from the oscilloscope. Is the message still displayed? If so, remove the AP033. Is the
message still displayed? If so, the oscilloscope should be returned for service.
8. If, after removing the AP033, the Power Supply Overload error message is not displayed, the
problem may be either the probe or the oscilloscope. Repeat the test with a different ProBus
accessory. If the message does not return with a different accessory, the AP033 may be
defective and should be returned for service.
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B. Incorrect Frequency Response
Possible causes are a defective probe or oscilloscope, poor connections, or poor grounding.
1. Verify that the BW limiting of the oscilloscope is off.
2. Connect the probe to another oscilloscope. If the probe now measures properly, the problem
may be in the oscilloscope.
3. If the probe behaves as if it is ac-coupled at high frequency, check for an open input
connection.
4. Poor frequency or transient response and AC gain errors may result when one of the two input
connections is open.
5. Excessive “ring” and other transient problems can result from excessive input lead length. To
test this, shorten the input leads to less than 1 cm. If the transient response changes
significantly, the lead parasitics are the cause.
C. DC Errors
Incorrect DC gain requires recalibration or factory repair. This can be determined by completing the
gain checks in the Performance Verification Procedure.
1. Extremely high source resistance will result in DC gain errors. Check the probe accuracy with
the oscilloscope calibrator signal.
2. Verify that the probe is not being overdriven into clipping for its current gain setting.
3. Excessive offset can result from large changes in ambient temperature. Remove the input
signal from the probe and repeat the Autobalance cycle. With the Offset set to zero, did the
trace return to the center of the graticule?
D. Poor Common Mode Rejection
Use the 1-kHz calibrator signal from the oscilloscope to check common mode rejection. With both
the + input and – input connected to the calibrator signal, a flat line at zero volts should be seen on
the graticule.
1. Check the probe with the plug-on attenuator installed and removed. If excessive common
mode signal appears only when the attenuator is present, the attenuator may need to be
rematched to the probe. Use the procedure listed in this section to match the attenuator.
2. If the common mode signal appears when the probe is connected to the test circuit, but not
when it is attached to the calibrator, the problem may be caused by large mismatches in the
source impedance. Try connecting both inputs to one of the input signals in the test circuit,
then the other. If the common mode signal disappears, try probing lower impedance points
within the circuit.
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AP033 Active Differential Probe
Returning a Probe
Return a probe for calibration or service by contacting your local Teledyne LeCroy sales
representative. They tell you where to return the product. All returned products should be
identified by both model and serial number. Provide your name and contact number, and a
description of the defect or failure (if possible).
Products returned to the factory require a Return Material Authorization (RMA) acquired by
contacting your nearest Teledyne LeCroy sales office, representative or the North America
Customer Care Center.
Return shipment should be prepaid. Teledyne LeCroy cannot accept COD or Collect Return
shipments. We recommend air-freighting.
1. Contact your local Teledyne LeCroy sales or service representative to obtain a Return Material
Authorization.
2. Remove all accessories from the probe. Do not include the manual.
3. Pack the probe in its case, surrounded by the original packing material (or equivalent) and box.
4. Label the case with a tag containing
The RMA
Name and address of the owner
Probe model and serial number
Description of failure
5. Package the probe case in a cardboard shipping box with adequate padding to avoid damage
in transit.
6. Mark the outside of the box with the shipping address given to you by the Teledyne LeCroy
representative; be sure to add the following:
ATTN:
FRAGILE
7. Insure the item for the replacement cost of the probe.
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8. If returning a probe to a different country, also:
Mark shipments returned for service as a “Return of US manufactured goods for
warranty repair/recalibration.”
If there is a cost involved in the service, put the service cost in the value column and
the replacement value of the probe in the body of the invoice marked “For insurance
purposes only.”
Be very specific as to the reason for shipment. Duties may have to be paid on the value
of the service.
Available Accessories
Teledyne LeCroy
Part Number
Description
PK033
Accessory Kit, AP033 without AC Coupler
and Attenuator
AP03X-FLEX-LEAD
Flex Lead
405400003
Offset Pin, package of 10
AP033-ATTN
Plug-On Attenuator, /10, AP033
AP03X-AC-COUPLER
Plug-On AC Coupler, AP033/AP034
922260-00
Operator’s Manual, AP033, English
922260-00 Rev A
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AP033 Active Differential Probe
Matching Procedure for ÷10 Plugs
The ÷10 Plug-on attenuator provided as a standard accessory with the AP033 is calibrated to match
the specific probe it was shipped with. Individual probes will have small variations in parasitic
capacitance within the input circuits. To obtain maximum common mode rejection performance,
the attenuators are calibrated to match a specific probe during the manufacturing process. In order
to preserve the maximum Common Mode Rejection, do not interchange external attenuators
between probes.
The Plug-on AC coupling adapter is not matched to a specific probe and, therefore, does not need
to be matched. If the ÷Plug-on attenuators become accidentally mixed between probes, you
can use the procedure listed below to restore the compensation match. This adjustment does not
affect any of the parameters in the warranted specifications. Therefore, the required test
equipment does not need to be calibrated.
NOTE: The AP033 and AP033 Active Differential Probes have different input capacitance. The 10
Plug-on attenuator supplied with model AP033 cannot be properly adjusted for use with model
AP033. Make sure that the attenuator is marked “AP033” before attempting this procedure.
Equipment Required
Test Oscilloscope
The oscilloscope must support ProBus. With a non-ProBus oscilloscope, use the ADPPS power
supply.
Signal Source
Low frequency square wave: Frequency 50 Hz to 5 kHz, Amplitude 1 V to 10 V. The output
waveform must have a square corner and flat top with minimum overshoot suitable for adjusting
compensation. The generator should have trigger output, or use a BNC Tee connector and separate
BNC cable from the output to provide the trigger signal for the test oscilloscope.
Interconnect Cable
This is for connecting the output of the signal source to the probe. A BNC cable and a pair of small
alligator clips or “lead grabber” adapter (Pomona #3788) may be used. 0.025 in. (0.635 mm)
Square Pins (3 required). The pins from the header supplied in the probe accessory kit are suitable.
Tools
Flat bladed screwdriver, 0.040 in. (1 mm) wide
Adjustment Tool: 0.025 in. (0.635 mm) square head
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Note: You can fabricate the Adjustment Tool by flattening the end of a 0.025 in. (0.635 mm)
square pin with a file. Insert the pin into a short length of rigid plastic tubing to serve as a handle.
Procedure
1. Attach the AP033 to the test oscilloscope. If the test oscilloscope is not equipped with ProBus,
use the ADPPS to provide power for the AP033.
2. Attach the ÷Attenuator Adapter to the AP033 probe tip.
3. Insert 0.025 in. (0.635 mm) square pins into the +, -, and input connectors of the
Attenuator Adapter.
4. Attach the interconnect cable to the output of the signal source.
5. Attach the Trigger Out signal from the signal source to the External Trigger Input of the test
oscilloscope. If the signal source does not have a separate Trigger Out signal, use a BNC Tee
connector in the output. Run one cable to the External Trigger Input of the test oscilloscope.
Connect the other to the probe inputs.
6. Using the alligator clips on the end of the interconnect cable, connect the signal source ground
to the square pin on the ÷Attenuator Adapter’s “-“ input. Attach the signal output to the
square pin on the ÷Attenuator Adapter’s “+” input.
7. Turn on the test oscilloscope. Set the AP033 GAIN to X10. The EFFECTIVE GAIN indicator for
÷should be lit. (NOTE: If the X1 EFFECTIVE GAIN indicator is lit rather than the ÷10, make
sure that the adapter installed on the probe tip is the ÷Attenuator, and not the AC
Coupler.)
8. Set the test oscilloscope Volts/Div to 200 mV (for Teledyne LeCroy oscilloscopes with ProBus)
or 20 mV/Div when using the ADPPS with an oscilloscope without scale factor correction; 5
s/Div; AUTO trigger mode; Trigger source: External. Set the Bandwidth Limiting to 20-30 MHz
and Average the waveform 1:31 to reduce noise.
9. Turn on the signal source. Set the output frequency to approximately 5 kHz. Set the output
amplitude to approximately 1 Volt.
10. Adjust the test oscilloscope trigger level for a stable trace. If necessary, use the probe offset to
position the waveform to show the square corner of the test signal.
NOTE: Do not use the oscilloscope offset or position controls to reposition the trace. Many of
the signal generators used for compensation calibration only have square corners on one of the
two edges of the output waveform. (Rising or falling edge, but not both.) Be sure to display the
correct edge for this step.
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AP033 Active Differential Probe
11. Using the square adjustment tool, adjust the +LF Comp (See Figure 6) to achieve the best square
corner and flat top of the displayed waveform. Note that the added capacitance of the
adjustment tool may change the compensation of the waveform when it is inserted. The correct
adjustment is achieved when the best corner is displayed with the adjustment tool removed
.
Figure 6, ÷10 Attenuator Adjustment Locations
12. Move the connections on the interconnect cable so the signal generator ground is connected to
the square pin inserted in the ground connector of the Attenuator Adapter. Connect the signal
generator output to BOTH the + input and – input square pins in the Attenuator Adapter.
13. Set the signal generator frequency to about 50 Hz, and the output amplitude to about 10 V.
14. Set the test oscilloscope Volts/Div to 20 mV (for Teledyne LeCroy oscilloscopes with ProBus) or
2 mV/Div when using the ADPPS with an oscilloscope without scale factor correction; set the
time scale to 2 ms/Div. It may be necessary to increase the averaging to 1:127 to remove noise.
15. The displayed waveform is the common mode feedthrough. Using the adjustment screwdriver
with the flat blade, adjust the DC Atten. Balance (Figure 6) to minimize the amplitude of the flat
portions of the displayed waveform. This adjustment only affects the flat portions of the square
wave. Do not be concerned with any overshoot at the transitions.
16. Reduce the Test Oscilloscope Averaging weighting to 1:31. Return the Volts/Div to 200 mV (for
Teledyne LeCroy oscilloscopes with ProBus) or 20 mV/Div when using the ADPPS with an
oscilloscope without scale factor correction, and the Time/Div to 5 s.
17. Return the signal source output frequency to approximately 5 kHz. Set the output amplitude to
approximately 1 Volt.
18. Using the 0.025 in. square adjustment tool, adjust the –LF Comp (Figure 6) to minimize the
amplitude of overshoot during the transition of the displayed waveform. It may not be
possible to completely eliminate the overshoot. As with the +LF Comp adjustment, the added
capacitance of the adjustment tool may change the amplitude of the waveform when it is
inserted into the adjustment. The correct adjustment is achieved when the overshoot is
minimized.
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Performance Verification
This procedure can be used to verify the warranted characteristics of the AP033 Active Differential
Probe. You can do the performance verification without removing the instrument covers and
exposing yourself to hazardous voltages.
Adjustment should only be attempted if a parameter measured in the Performance Verification
Procedure is outside of the specified limits. Adjustment should only be performed by qualified
personnel.
The recommended calibration interval for the model AP033 Active Differential Probe is one year.
The complete performance verification procedure should be performed as the first step of annual
calibration. You can record test results on a photocopy of the Test Record at the end of this
section.
Test Equipment Required
Table 3 lists the test equipment and accessories (or their equivalents) that are required for
performance verification of the AP033 Active Differential Probe.
This procedure has been developed to minimize the number of calibrated test instruments
required. Only the parameters listed in boldface in the “Minimum Requirements” column must be
calibrated to the accuracy indicated.
Because the input and output connector types may vary on different brands and models of test
instruments, additional adapters or cables may be required.
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AP033 Active Differential Probe
Table 3, Performance Verification Test Equipment
Description
Minimum Requirements
Example Test Equipment
Wide Band Oscilloscope
(see note)
Minimum 1 GHz bandwidth
Teledyne LeCroy Wavepro 950
2 mV to 5 V scale factors ProBus
interface equipped
2% vertical accuracy
Digital Multimeter
Function Generator
DC: 0.1% accuracy
Agilent Technologies 34401A
AC: 0.2% accuracy to measure 200
mV and 2 V rms @ 1 kHz 5½ digit
resolution
Fluke 8842A-09
Sine Wave and Square Wave output
waveforms
Agilent Technologies 33120A
Keithley 2001
Stanford Research Model DS340
20 Vp-p into 1 MΩ
70 Hz to 10 MHz frequency range
Leveled Sine Wave Generator
2
Relative output level accurate to 3%
flatness from 50 to 500 MHz and 50
kHz. Output adjustable to 2 Vp-p
Tegam SG504 with TM series
mainframe A high frequency sine
wave generator calibrated using
semi-automated software leveled
with a power meter may be
substituted.
Terminator, in-line, BNC
50 Ω ±2% coaxial termination
Pomona 4119-50
Terminator, precision,
BNC 50 Ω ±0.2%
Teledyne LeCroy TERM-CF01
Attenuator, BNC
50 Ω ±2%, ÷10 (20 dB)
Pomona 4108-20dB
Attenuator, BNC
50 Ω ± 2%, ÷2 (6 dB),
Pomona 4108-6dB
BNC coaxial cable (2 required)
male-male BNC, 50 Ω, 36 in.
Pomona 5697-36
Calibration Fixture
ProBus Extension Cable
Teledyne LeCroy PROBUS-CF01
Calibration Fixture
AP033/AP034 Calibration Fixture
Teledyne LeCroy AP03x-CF01
Banana Plug adapter
BNC female-to-banana plug
Pomona 1269
NOTE: If a Teledyne LeCroy ProBus equipped oscilloscope is not available, you may use an
alternate oscilloscope that meets the other minimum specifications listed, and the model ADPPS
power supply, to perform the performance verification procedure. The input termination of the
alternate oscilloscope must be set to 50 Ω and the offset or position must remain at center screen.
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Preliminary Procedure
1. Connect the AP033 Active Differential Probe to the female end of the ProBus Extension Cable.
Connect the male end of the ProBus extension cable to Channel 1 of the oscilloscope.
2. Turn the oscilloscope on and allow at least a 30- minutes warm-up time for the AP033 and test
equipment before performing the Verification Procedure.
3. Turn on the other test equipment and allow these to warm up for the time recommended by
the manufacturer.
4. While the instruments are reaching operating temperature, make a photocopy of the
Performance Verification Test Record (located at the end of this section), and fill in the
necessary information.
The warranted characteristics of the AP033 Active Differential Probe are valid at any temperature
within the Environmental Characteristics listed in the Specifications. However, some of the other
test equipment used to verify the performance may have environmental limitations required to
meet the accuracy needed for the procedure. Make sure that the ambient conditions meet the
requirements of all the test instruments used in this procedure.
Procedure
NOTE: The operation of the controls of the AP033 may differ depending on which version of
firmware is loaded in the Teledyne LeCroy oscilloscope. In versions 8.1.0 and higher, the offset
controls on the front panel of the probe are disabled. The AP033 offset is controlled by the OFFSET
knob in the oscilloscope CHANNEL section. In software versions 7.6.0 to 8.0.x, probe offset is
controlled through one of the menu knobs while the “Coupling” menu is displayed. In versions
7.8.0 and higher, you have the option of selecting manual or automatic gain control. The
oscilloscope defaults to AUTOMATIC mode. This procedure is best performed with the
oscilloscope set to MANUAL gain control. Gain control can be set via the “Coupling” menu or, for XStream oscilloscopes, the Channel dialog for the channel to which the probe is connected.
A. Check Gain Accuracy
1. From the oscilloscope display, select the channel that the AP033 is connected to (channel 1. Set
the AP033 Atten/Gain to Manual, the Probe Gain to X1, and the Probe Atten to /1. (/1 is the
same as ÷1)
2. If necessary, set the probe offset to 0.000 V by rotating the OFFSET knob in the CHANNEL
section of the oscilloscope.
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AP033 Active Differential Probe
3. Using a BNC female-to-female adapter, connect one end of a BNC cable to the probe end of the
ProBus Extension Cable. Connect the Precision 50Ω Terminator to the other end of the BNC
cable.
4. Connect one end of a second BNC cable to the output of the Function Generator. Attach the
BNC-to-dual-male banana plug adapter to the free end of the second BNC cable. Connect the
banana plugs to the Digital Multimeter (DMM).
5. Set the DMM to measure AC Volts.
6. Set the mode of the Function Generator to Sine Wave; the frequency to approximately 1 kHz;
and the output amplitude to approximately 200 mV rms, as measured by the DMM.
7. Record the measured amplitude to 100 μV resolution in the Test Record.
8. Unplug the output cable from the DMM. Remove the BNC-to banana plug adapter from the
end of the cable.
9. Autobalance the AP033 by pressing the AUTOBALANCE menu button.
10. Carefully align the four pins that correspond to the Differential Drive No Termination portion of
the AP03x- CF01 Calibration Fixture with the input receptacles in the AP033 probe head. Press
the probe into the fixture to fully engage the pins.
11. Connect the banana plugs of the precision terminator to the digital multimeter (DMM)
12. Connect the free end of the output cable from the Function Generator to the Differential Drive
No Termination connector of the AP033/AP034 Calibration Fixture.
13. After the DMM reading has stabilized, record the measured output amplitude to 100 μV
resolution in the Test Record.
14. Divide the measured output voltage (recorded in step A-13) by the sine wave generator output
voltage (probe input voltage) from step A-7. Subtract 1.0 from the ratio and multiply the result
by 100 to get the error in percent.
15. Record the answer to two significant places (±x.xx%) on line A-15 in the Test Record.
16. Verify that the X1 gain error is less than ±2%.
17. Change the Probe Atten to /10 and the Probe Gain to X10.
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18. After the DMM reading has stabilized, record the measured output amplitude to 100 μV
resolution in the Test Record.
19. Divide the measured output voltage recorded in step A-18 by the sine wave generator output
voltage (probe input voltage) from step A-7. Subtract 1.0 from the ratio and multiply the
result by 100 to get the error in percent.
20. Record the answer to two significant places (±x.xx%) on line A-20 in the Test Record.
21. Verify that the X10 gain error is less than ±2%.
22. Divide the Sine Wave Generator output voltage recorded in step A-7 by 10. Record the result
as “Expected Probe Output Voltage” in the Test Record.
23. Return the Probe Gain to X1. Leave the Probe Atten set to /10.
24. After the DMM reading has stabilized, record the measured output amplitude to 10 μV
resolution in the Test Record.
25. Calculate the error by dividing the measured output voltage recorded in step A-22. Subtract 1.0
from this ratio and multiply by 100 to get the error in percent.
26. Record the calculated error to two decimal places (±x.xx%) as ÷10 Gain Error’ in the Test
Record.
27. Verify that the ÷10 gain error is less than ±2%.
28. Disconnect both BNC cables from the test setup.
B. Check High Frequency Common Mode Rejection Ratio (CMRR)
NOTE: Common Mode Rejection Ratio (CMRR) is defined as the Differential Mode Gain divided by
the Common Mode Gain (normalized inverse of the Common Mode response). At higher
frequencies where the bandwidth of the amplifier begins to attenuate the differential mode signal,
both the differential mode gain and common mode gain must be measured to derive the CMRR.
1. Disconnect the ProBus Extension cable from the AP033 and the oscilloscope. Reconnect the
AP033 directly to the Channel 1 input of the oscilloscope.
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AP033 Active Differential Probe
2. Carefully move the AP033 probe head from the Differential Drive No Termination connector of
the AP033/AP034 Calibration Fixture to the Differential Drive 50 Ohm Termination connector.
Make sure that the probe is fully engaged in the fixture.
3. Set the oscilloscope to display channel 1.Set Coupling to DC 1 MΩ, and Global BWL to Off.
Autobalance the AP033 by pressing the AUTOBALANCE button twice. Set the oscilloscope
trigger mode to AUTO.
4. If necessary, center the trace with the Probe Offset (or Channel OFFSET) knob.
5. Connect the output of the leveled sine wave generator to the Differential Drive 50 Ohm
Termination connector of the AP033/AP034 Calibration Fixture. If using a model SG504
generator, insert a ÷2 50Ω BNC attenuator between the generator output and the test fixture
input.
6. Set the leveled sine wave generator frequency to 50 kHz, and the amplitude to approximately
300 mVp-p. When using a model SG504 generator, set the output to 0.6V pk-pk at the output
which will correspond to 300 mV at the output of the ÷2 attenuator.
7. Set the oscilloscope vertical scale factor to 50 mV/div and the horizontal scale factor to 10
μsec/div. Set the Trigger source to Channel 1. Adjust the trigger level for a stable display. Turn
on Math Channel A. Press MATH SETUP, then REDEFINE A. Set the A Math type to Average, Avg
Type to Continuous, with 1:15 weighting, of channel 1. Turn off the trace 1 display.
8. Adjust the output amplitude of the leveled sine wave generator for a display of exactly 6
divisions (300 mV) peak to peak.
9. Change the leveled sine wave generator frequency to 250 MHz, taking care not to change the
output amplitude.
10. Change the oscilloscope horizontal scale to 1 ns/div. In the SETUP TIMEBASE menu, select RIS
Sampling. If necessary, turn the channel 1 display back on and adjust the trigger for a stable
trace. Once a stable trace has been achieved, turn off the channel 1 trace to only display the
averaged waveform.
11. Measure the peak-to-peak output amplitude of the AP033. Record the reading to two-digit
resolution (xx0 mV) as ‘Probe Output Voltage at 250 MHz’ in the Test Record.
12. Divide the measured output amplitude recorded in step B-11 by 300 mV. Record the answer to
two-digit resolution (0.xx) in the Test Record. This is the ‘Differential Mode Gain at 250 MHz’.
13. Move the leveled sine wave generator output cable from the Differential Drive 50 Ohm
Termination connector of the AP033/AP034 Calibration Fixture to the channel 2 input of the
oscilloscope.
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14. Carefully move the AP033 probe head from the Differential Drive 50 Ohm Termination
connector of the AP033/AP034 Calibration Fixture to the Common Mode Drive 50 Ohm
Termination connector. Make sure the probe is fully engaged in the fixture.
15. Set the oscilloscope to display channel 2, channel 2 vertical scale to 0.5 Volt/div, channel 2
input coupling to DC50Ω, and trigger source to channel 2. If necessary, adjust the trigger
level for a stable display.
16. Set the sine wave generator output amplitude to exactly 2 Vp-p. (4 divisions on the
oscilloscope).
17. Remove the leveled sine wave generator output cable from the oscilloscope and reconnect
it to the Common Mode Drive 50 Ohm Termination input connector of the AP033/AP034
Calibration Fixture.
18. Set the oscilloscope to display Math channel A (Averaged AP033 Output), and trigger
source to channel 1.
19. Increase the channel 1 vertical sensitivity as needed to view the signal.
20. Measure the peak to peak amplitude of the averaged waveform. This is the common mode
signal.
NOTE: The amplitude of the Common Mode signal should be relatively small. If the output
waveform appears to be a 1-Volt square wave, verify that the Common Mode Drive 50
Ohm Termination connector of the AP033/AP034 Calibration Fixture is being used, and
not the Differential Drive 50 Ohm Termination connector.
21. Record the Common Mode signal amplitude to two-digit resolution (xx0 mV) in the Test
Record as ‘Common Mode Signal at 250 MHz’.
22. Calculate the Common Mode Gain by dividing the Common Mode signal recorded in step
B-21 (in mV) by 2,000 mV.
23. Record the result to two significant places as ‘Common Mode Gain at 250 MHz’ in the Test
Record. (Keep all of the leading zeros or use scientific notation.)
24. Calculate the Common Mode Rejection Ratio (CMRR) at 200 MHz by dividing the
Differential Mode Gain at 250 MHz as recorded in step B-12 by the Common Mode Gain
recorded in step B-23.
25. Record the result as ‘Common Mode Rejection Ratio at 250 MHz’ in the Test Record.
26. Verify that the CMRR at 250 MHz is greater than 5:1 (14 dB).
27. Disconnect the output and frequency reference cables from the leveled sine wave
generator.
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AP033 Active Differential Probe
C. Check Low Frequency CMRR
NOTE: The attenuation of the AP033 Active Differential Probe below 10 MHz is so insignificant
that the Differential Mode Gain can be assumed to be unity (1.0). Because greater amplitudes are
required to measure the higher CMRR specifications at low frequencies, the Function Generator
will be used in place of the leveled sine wave generator for the low frequency CMRR test.
1. Carefully move the AP033 probe head from the Common Mode Drive 50 Ohm Termination
connector of the AP033/AP033 Calibration Fixture to the Common Mode Drive No Termination
connector. Make that sure the probe is fully engaged in the fixture.
2. Set the oscilloscope to display channel 2, the channel 2 input coupling to DC1 MΩ, the channel
2 vertical scale to 5 Volt/div, the horizontal scale to 5 ms/div, and the trigger source to channel
2. Set BW limiting on channels 1 and 2 to 25 MHz.
3. Verify the settings: Coupling to DC 1MΩ, Global BWL to Off, AP033 Attenuation/Gain to
Manual, Probe Attenuation to /1, and Probe Gain to X1.
4. Attach a BNC cable from the output of the Function Generator to the BNC T adapter. Attach
the BNC T adapter on the output connector of the Function Generator. Connect a BNC cable
from one end of the BNC T adapter to channel 2 of the oscilloscope. Connect a second BNC
cable from the remaining end of the BNC T adapter to the Common Mode Drive No
Termination input connector of the AP033/AP034 Calibration Fixture.
CAUTION: Make sure that you use the Common Mode Drive No Termination connection.
Prolonged application of the power levels used in the low frequency common mode test may
damage the termination resistance in either 50 Ohm Termination input of the AP033/AP034
calibration fixture.
5. Set the sine wave generator frequency to 70 Hz, output amplitude to 8 Vp-p, (eight divisions
on the oscilloscope). If necessary, adjust the trigger level for a stable display.
6. Set the oscilloscope to display channel 1, but leave the trigger source set to channel 2. Set the
vertical scale of channel 1 to 2 mV/div. Create a math waveform on channel A defined as the
Average of channel 1. Set the average factor as necessary to reduce noise. Turn off the
waveform display of all channels except Math A waveform.
7. Increase the zoom of Math waveform A as needed to measure the peak-to-peak amplitude.
This is the common mode signal.
8. Record the displayed ‘Common Mode Signal at 70 Hz’ to two-digit resolution (0.xx mV) in the
Test Record.
32
922260-00 Rev A
Operator’s Manual
9. Calculate the Common Mode Rejection Ratio (CMRR) at 70 Hz by dividing 8,000 mV by the
measured Common Mode Signal recorded in step C-8 (direct reciprocal of the Common Mode
Gain). Record the result to two-digit resolution (xx,000 : 1) in the Test Record.
10. Verify that the Common Mode Rejection Ratio at 70 Hz is greater than 3,160:1 (70 dB).
11. Set the oscilloscope to display channel 2. Change the horizontal scale factor to 0.5 s/division.
Set the BWL on channels 1 and 2 to 200 MHz.
12. Change the frequency of the Function Generator to 1 MHz.
13. Adjust the trigger level as necessary for a stable display. Adjust the Function Generator
amplitude as needed to maintain 8.0V pk-pk as measured on channel 2.
14. Turn off the oscilloscope channel 2 display; turn on the display of channel 1 and Math
waveform A (averaged channel 1). Adjust the scale factor of channel 1 and the Zoom of Math A
as necessary to accurately measure the amplitude of the averaged waveform.
15. Record the displayed ‘Common Mode Signal at 1 MHz’ to two-digit resolution in the Test
Record.
16. Calculate the Common Mode Rejection Ratio (CMRR) at 1 MHz by dividing 8,000 mV by the
measured Common Mode Signal recorded in step C-22. Record the result in the Test Record.
17. Verify that the Common Mode Rejection Ratio at 1 MHz is greater than 1,000:1 (60 dB).
18. Remove all cables and test fixtures from the AP033 probe.
This concludes the Performance Verification of the AP033. Complete and file the results recorded
in the AP033 Performance Verification Test Record as required by your quality procedures. Apply a
suitable calibration label to the AP033 housing as required.
AP033 Performance Verification Test Record
This record can be used to record the results of measurements made during the performance
verification of the AP033 Active Differential Probe.
Photocopy the next page and record the results on the copy. File the completed record as required
by applicable internal quality procedures.
The section in the test record corresponds to the parameters tested in the performance verification
procedure. The numbers preceding the individual data records correspond to the steps in the
procedure that require the recording of data. Results to be recorded in the column labeled “Test
Result” are the actual specification limit check. The test limits are included in all of these steps.
Other measurements and the results of intermediate calculations that support the limit check are
to be recorded in the column labeled “Intermediate Results.”
Permission is granted to reproduce these pages for the purpose of recording test results.
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AP033 Active Differential Probe
Model:
Serial Number:
AP033
Asset or Tracking Number:
Date:
Technician:
MODEL
SERIAL NUMBER
CALIBRATION
DUE DATE
OSCILLOSCOPE
DIGITAL MULTIMETER
LEVELED SINE WAVE GENERATOR
HF SINE WAVE GENERATOR
1
FUNCTION GENERATOR
N/A
1 The
function generator provides stimulus for making relative measurements. The output amplitude of the generator is
measured with the DMM or oscilloscope in the procedure. Thus, the generator is not required to be calibrated.
Step
Description
Intermediate Data
Test Result
Gain Accuracy
A-7
Sine Wave Generator Output Voltage
________________ mV
A-13
Probe Output Voltage
________________ mV
A-15
Gain Error (Test Limit ≥ ±2%)
_________________ %
High Frequency Common Mode Rejection Ratio (CMRR)
B-13
Common Mode Signal at 100 MHz
B-15
CMRR at 100 MHz (Test Limit ≥ 18:1)
________________ mV
_________________ :1
Low Frequency Common Mode Rejection Ratio
C-7
Common Mode Signal at 70 Hz
C-8
CMRR at 70 Hz (Test Limit ≥ 10 000:1)
C-14
Common Mode Signal at 1 MHz
C-15
CMRR at 1 MHz (Test Limit ≥ 100:1)
34
________________ mV
_________________ :1
________________ mV
_________________ :1
922260-00 Rev A
Operator’s Manual
Adjustment Procedure
Introduction
You can use this procedure to adjust the AP033 Active Differential Probe to meet the warranted
specifications. This procedure should only be performed if the instrument fails the Performance
Verification tests. If the probe cannot be adjusted to meet the Performance Verification limits,
repair may be necessary. To ensure instrument accuracy, check the calibration of the AP033 Active
Differential Probe every year. Before calibration, thoroughly clean and inspect this unit as discussed
in the “Cleaning” section.
Completion of each step in the Adjustment Procedure ensures that the differential probe meets
specifications. Some of the adjustments interact with other parts of the circuitry. Therefore, it is
necessary that all adjustments be performed in the order listed. For best overall instrument
performance, make each adjustment to the exact setting, even when adjustment is within the
limits stated in the procedure.
Adequate guard bands were designed into the AP033 Active Differential Probe to ensure that it will
meet or exceed published specifications over the entire operating temperature range. To continue
to meet the environmental specifications, all adjustments must be performed in a controlled
environment with an ambient temperature of 25 ±5 °C. The AP033 Active Differential Probe must
also be at stable operating temperature before performing adjustments.
CAUTION: The adjustment procedure will require removal of the probe covers. These covers
are part of the ESD protection system of the AP033 Active Differential Probe. To protect the probe,
you should perform the entire procedure on a static dissipating work surface Wear an antistatic
grounding wrist strap and follow standard static control procedures.
The probe tip housing provides physical rigidity to the input pins of the probe. When the covers are
removed, observe extra caution to avoid breaking the probe tip receptacles when mating the probe
to the calibration fixture.
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AP033 Active Differential Probe
Test Equipment Required
The table on the next page lists the test equipment and accessories, or their equivalents, that are
required for complete calibration. Specifications given for the test equipment are the minimum
necessary for accurate calibration. All test equipment is assumed to be correctly calibrated and
operating within the specifications listed. Detailed operating instructions for the test equipment
are not given in this procedure. Refer to the test equipment manual if more information is needed.
If alternate test equipment is substituted, control settings or calibration equipment setups may
need to be altered. Alternate models of test equipment may have different connector styles
requiring adapters not included in the equipment list.
Table 4, Adjustment Test Equipment
Description
Wide Band Oscilloscope *
Digital Multimeter
Minimum Requirements
Example Test Equipment
500 MHz bandwidth
Teledyne LeCroy LT342
2 mV to 200 mV vertical scale
factors ProBus interface
equipped* 2% vertical accuracy
Teledyne LeCroy LC344A
0.1% DC volts accuracy at 0.4 V
0.2% AC volts accuracy at 2 V
and 1 kHz
Agilent Technologies 34401A
5½ digit resolution
Fluke 8842A-09
Keithley 2001 with test leads
0.01 mV AC volts resolution
Function Generator
Fast Rise Pulse Generator
Sine and square wave output
Agilent Technologies 33120A
20 Vp-p into 1 MΩ
Stanford Research Model DS340
50 Hz to 1 MHz frequency Range
Sync. or Freq. Reference output
Leader LAG-120B
Risetime 400 mV into 50 Ω
Over/Undershoot
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