LeCroy DA18000AC Instruction Manual

LeCroy DA18000AC

Differential Amplifier

Instruction Manual

Revision A – June 2006

LeCroy Corporation
700 Chestnut Ridge Road
Chestnut Ridge, NY 10977-6499
Tel: [phone], Fax: [phone]

Internet: www.lecroy.com

Warr anty

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, 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 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 non­authorized service facility.

The customer will be responsible for the transportation and insurance charges for the return of prod­ucts to the service facility. 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. LeCroy
shall not be liable for any special, incidental, or consequential damages, whether in contract or oth­erwise.

© 2006 by LeCroy Corporation. All rights reserved.

LeCroy, ActiveDSO, WaveLink, JitterTrack, WavePro, WaveMaster, WaveSurfer, and
Waverunner are registered trademarks of LeCroy Corporation. Other product or brand
names are trademarks or requested trademarks of their respective holders. Information in
this publication supersedes all earlier versions. Specifications subject to change without
notice.

Manufactured under an
ISO 9000 Registered
Quality Management System

Visit www.lecroy.com to view the
certificate.

DA18000AC-OM-E Rev A
914190-00 Rev A

This electronic product is sub­ject to disposal and recycling
regulations that vary by country
and region. Many countries pro­hibit the disposal of waste elec­tronic equipment in standard
waste receptacles.

For more information about
proper disposal and recycling of
your LeCroy product, please
visit www.lecroy.com/recycle.

DECLARATION OF CONFORMITY

according to ISO/IEC Guide 22 and EN 45014:1998

Manufacturer’s Name: LeCroy Corporation

Manufacturer’s Address: 700 Chestnut Ridge Road

herewith declare that

Product(s) Name: Differential Probe

Model Number(s): DA18000AC

including all their options are in conformity with the provisions of the following EC directive(s), including the latest
amendments, and with national legislation implementing these directives:

and that conformity with Council Directive 73/23/EEC is based on

EN 61010-031: 2002 Safety requirements for electrical equipment for measurement, con-

and that conformity with Council Directive 89/336/EEC is based on

EN 61326/A3:2003 EMC requirements for electrical equipment for measurement, con-

Emissions EN 55011/A2:2002 Radiated Emissions

Immunity: EN 61000-4-2/A2:2001 Electrostatic Discharge

Chestnut Ridge, NY 10977
USA

73/23/EEC Low Voltage Directive
89/336/EEC EMC Directive

trol and laboratory use
Part 031: Safety requirements for hand -held amplifier assemblies for
electrical measurement and test

trol and laboratory use

EN 61000-4-3/A1:2003 RF Radiated Electromagnetic Field

By: Scott Bausback European Contact:

Chief Operating Officer Your local LeCroy Sales Office or

Place: LeCroy Corporation LeCroy Europe GmbH

700 Chestnut Ridge Road Waldhofer Str. 104
Chestnut Ridge, NY 10977 D-69123 Heidelberg
USA Germany

Date: June 12, 2006 Tel: [phone]

Warning: This is a Class A product. In a domestic environment this product may cause radio interference, in
which case the user may be required to take adequate measures.

DA18000AC-OM-E Rev A iii

Fax: [phone]

BLANK PAGE

iv A18000AC-OM-E Rev A

Table of Contents

Safety Information ............................................................................. 1-1

SAFETY SYMBOLS ...........................................................................................1-1

OPERATOR SAFETY ........................................................................................1-1

OPERATING ENVIRONMENT ..........................................................................1-2

Overview ............................................................................................. 2-1

DESCRIPTION ..................................................................................................2-1

APPLICATIONS .................................................................................................2-1

STANDARD ACCESSORIES ............................................................................2-1

Components and Accessories ......................................................... 3-1

STANDARD ACCESSORIES ............................................................................3-1

Type K Input Leads ....................................................................................3-1

Type K ³2 Attenuator ..................................................................................3-1

Operation ............................................................................................ 4-1

HANDLING THE AMPLIFIER ............................................................................4-1

TYPE K CONNECTORS ....................................................................................4-1

COMPATIBILITY ................................................................................................4-1

CONNECTING THE AMPLIFIER TO A LECROY SERIAL DATA ANALYZER .4-1

AUTOCOLOR ID ................................................................................................4-2

OPERATION WITH THE SDA 18000 ................................................................4-2

CONNECTING THE AMPLIFIER TO THE TEST CIRCUIT ...............................4-3

Type K Input Leads ....................................................................................4-3

USE OF DC ³2 ATTENUATOR ..........................................................................4-4

GROUNDING .....................................................................................................4-4

DYNAMIC RANGE .............................................................................................4-4

Care and Maintenance ....................................................................... 5-1

CLEANING ........................................................................................................5-1

SERVICE STRATEGY .......................................................................................5-1

RETURNING AN AMPLIFIER FOR CALIBRATION OR SERVICE ...................5-1

RETURNING AN AMPLIFIER TO A DIFFERENT COUNTRY ..........................5-2

REPLACEMENT PARTS ...................................................................................5-2

Reference Information ....................................................................... 6-1

DIFFERENTIAL MODE AND COMMON MODE ...............................................6-1

DIFFERENTIAL MODE RANGE AND COMMON MODE RANGE ....................6-1

COMMON MODE REJECTION RATIO .............................................................6-2

Performance Verification .................................................................. 7-1

INTRODUCTION ...............................................................................................7-1

TEST EQUIPMENT REQUIRED .......................................................................7-1

DA18000AC-OM-E Rev A v

DA18000AC Differential Amplifier

PRELIMINARY PROCEDURE .......................................................................... 7-2

VERIFICATION PROCEDURE ......................................................................... 7-2

Rise Time (20-80%) ................................................................................... 7-2

Specifications ..................................................................................... 8-1

NOMINAL CHARACTERISTICS ....................................................................... 8-1

General ...................................................................................................... 8-1

WARRANTED CHARACTERISTICS ................................................................ 8-1

TYPICAL CHARACTERISTICS ........................................................................ 8-2

ENVIRONMENTAL CHARACTERISTICS ........................................................ 8-3

PHYSICAL CHARACTERISTICS ...................................................................... 8-3

COMPLIANCE AND CERTIFICATIONS ........................................................... 8-4

CE Declaration of Conformity ..................................................................... 8-4

Appendix A ......................................................................................... A-1

PERFORMANCE VERIFICATION TEST RECORD .........................................A-1

ITEMS TESTED ................................................................................................A-1

EQUIPMENT USED: .........................................................................................A-1

TEST RECORD .................................................................................................A-1

vi DA18000AC-OM-E Rev A

Safety Information

1Safety Information

SAFETY SYMBOLS

The following symbols appear on the DA18000AC Differential Amplifier or in this manual
and alert the customer to important safety considerations.

Refer to the accompanying information or document to protect against
personal injury or damage to the instrument.

The CAUTION sign indicates a potential hazard. It calls attention to a
procedure, practice or condition, which, if not followed, could possibly
cause damage to the equipment. If a CAUTION is indicated, do not pro-

CAUTION

WARNING

CAUTION

OPERATOR SAFETY

To avoid personal injury and to prevent damage to the probe or any products connected to it,
review the following safety precautions. To avoid potential hazards, use the probe only as
specified.

ceed until its conditions are fully understood and met.

The WARNING sign indicates a potential hazard. It calls attention to a
procedure, practice or condition which, if not followed, could possibly
cause bodily injury or death. If a WARNING is indicated, do not proceed
until its conditions are fully understood and met.

The ESD sign indicates a potential hazard. It calls attention to the sus­ceptibility of the equipment to Electrostatic Discharge (ESD) induced
damage if anti-static measures are not taken.

To avoid damage to the amplifier or personal injury, comply with the
following:

ESD Sensitive: The amplifier tips of the DA18000AC amplifier are sen­sitive to electrostatic discharge (ESD). To avoid causing damage to the
amplifier, always follow anti-static procedures (wear wrist strap, etc.)

CAUTION

when using or handling the amplifier.

Connect amplifier to the measurement instrument before connecting
the probe test leads to a circuit/signal being tested.

CAUTION

Using the amplifier and/or the oscilloscope it is connected to in a man­ner other than that specified may impair their protection mechanisms.

CAUTION

Do not apply a voltage to any input that exceeds the maximum rating of
that input. (Section 9, Specifications).

WARNING

DA18000AC-OM-E Rev A 1-1

DA18000AC Differential Amplifier

Handle the probe with care as it has sharp tips that may cause bodily
injury if not handled properly.

WARNING

Do not use the amplifier in wet or explosive atmospheres.

WARNING

Do not use the amplifier if any part is damaged. All maintenance should
be referred to qualified service personnel.

CAUTION

OPERATING ENVIRONMENT

The DA18000AC Differential Amplifier is intended for indoor use and should be operated in
a clean, dry environment.

The design of the differential amplifier has been verified to conform to EN 61010-031 safety
standard per the following limits:

• Installation (Overvoltage) Category I: Refers to signal level which is applicable for
equipment measuring terminals that are connected to source circuits in which
measures are taken to limit transient voltages to an appropriate low level.

• Pollution Degree 2: Refers to an operating environment where normally only dry
non-conductive pollution occurs. Occasionally a temporary conductivity caused by
condensation must be expected.

###

1-2 DA18000AC-OM-E Rev A

Overview

2Overview

DESCRIPTION

The DA18000AC Differential Amplifier is a very high bandwidth differential amplifier with
50 Ω inputs and high common mode rejection, and is designed to be used exclusively with
the SDA 18000 Serial Data Analyzer.

The amplifier contains common circuitry such as power supply, communication and control
and AutoColor ID. The DA18000AC amplifier utilizes digital filtering to improve the system
frequency response. The response is corrected through the use of digital filters which are
specifically tailored through calibration to optimize the frequency flatness of the amplifier.
This provides the highest fidelity in eye pattern measurements.

Certificate of Calibration is supplied with each amplifier indicating that the system will meet
the specifications with those components listed in the Certificate.

ESD Sensitive: The inputs of the DA18000AC amplifier are sensitive to
Electrostatic Discharge (ESD). To avoid causing damage to the ampli­fier, always follow anti-static procedures (wear wrist strap, etc.) when

CAUTION

APPLICATIONS

The DA18000AC amplifier is ideally suited for acquiring differential signals common in high
speed serial data applications with fine pitch ICs and high lead count where high speed,
minimal loading and accurate jitter measurement are required.

• System Designers:

Designing systems using standard and ASIC components Use simulators and correlate
with lab measurements

• IC Designers:

Characterize new chip design

• Manufacturers of servers, PC Motherboards, Data routers, Disk drives

• High-speed SERDES

using or handling the type K connectors.

STANDARD ACCESSORIES

• Matched type K Input Cables (1 pair)

• Type K 6 dB attenuators (2)

• SAC-01 Soft Accessory Case with insert

• ESD Dissipating Wrist Strap

• DA18000AC Instruction Manual

• Certificate of Calibration

DA18000AC-OM-E Rev A 2-1

###

DA18000AC Differential Amplifier

BLANK PAGE

2-2 DA18000AC-OM-E Rev A

Components and Accessories

3Components and Accessories

STANDARD ACCESSORIES

Type K Input Leads

Type K ÷2 Attenuator

A matched pair of 50 Ω type K
Input Leads is provided for
direct cable connection to
female type K connectors of
the amplifier.

The type K attenuator can be
used to extend the differential
mode range or to improve the
VSWR by reducing reflections.

DA18000AC-OM-E Rev A 3-1

###

DA18000AC Differential Amplifier

BLANK PAGE

3-2 DA18000AC-OM-E Rev A

Operation

4Operation

HANDLING THE AMPLIFIER

The DA18000AC Differential Amplifier is a precision test instrument; exercise care when
handling and storing the amplifier. Always handle the amplifier by the body. Avoid putting
excessive strain on the attached cables or exposing the cables to sharp bends.

ESD Sensitive: The inputs of the DA18000AC amplifier are sensitive to
Electrostatic Discharge (ESD). To avoid causing damage to the ampli­fier, always follow anti-static procedures (wear wrist strap, etc.) when

CAUTION

TYPE K CONNECTORS

The type K connector of the DA18000AC amplifier is a precision coaxial connector that oper­ates up to 40 GHz. It is compatible with SMA, WSMA and 3.5 mm connectors.

To avoid misalignment of the male pin to the female contact, the male pin of the type K con­nector is made shorter than the SMA or 3.5 mm connector pins. This way the outer housing
is properly aligned prior to mating of the center conductors. Because of the new design, the
insertion force has been reduced from about 27 N in SMA and 3.5 mm connectors to about

2.3 N with the type K design. Type K connectors can be tightened to the same torque speci­fication as is used for type SMA, without damage.

When connecting SMA or 3.5 mm connectors, always align the male and female
parts before insertion to prevent damage to the female center connector.

Type K connectors use air for the dielectric, as opposed to PTFE resin in type SMA. Foreign
material such as excessive dust can enter the dielectric pocket and degrade the high fre­quency performance. Should this occur, remove the foreign material, using a jet of com­pressed air or gas. Disposable cans of compressed gas for dusting purposes are readily
available from photo or electronic equipment suppliers.

connecting cables to the input.

Note

Never insert an object into the connector in attempting to clean it. The
center contact can be easily bent out of position, destroying the connec-

CAUTION

tor.

COMPATIBILITY

The DA18000AC Differential Amplifier is designed to be used exclusively with the SDA
18000 Serial data Analyzer. However it includes frequency compensation data compatible
with lower BW WaveMaster, SDA, and DDA 5005 oscilloscopes.

CONNECTING THE AMPLIFIER TO A LECROY SERIAL DATA
ANALYZER

The DA18000AC amplifier has been designed for exclusive use with the SDA 18000 Serial
Data Analyzer.

For optimum performance and full bandwidth always connect the amplifier only to channel 1
of the SDA 18000.

DA18000AC-OM-E Rev A 4-1

DA18000AC Differential Amplifier

To attach the amplifier to the LeCroy oscilloscope, align the interface connector with the
input connector and push the interface toward the oscilloscope.

A click will be heard when the amplifier’s interface latches to the oscilloscope. This amplifier
also uses the thumb screws to secure the interface to the oscilloscope.

Thumb screws should be tightened finger tight only. Use of pliers or
another tool may overtighten the screws, resulting in damage to the

CAUTION

To remove the DA18000AC from the LeCroy oscilloscope, move the amplifier up and down
while pulling gently till a loud snap is heard indicating that the amplifier is unlatched from the
oscilloscope.

AUTOCOLOR ID

When the amplifier is connected to a SDA 18000, the LED will illuminate in the default color
of the channel to which the amplifier is connected.

OPERATION WITH THE SDA 18000

oscilloscope.

When the amplifier’s output connector is attached to the SDA 18000 oscilloscope’s input
connector, the oscilloscope will recognize the amplifier and activate the vertical channel
functions in the user interface. Figure 4-4. Refer to your oscilloscope’s instruction manual for
operations of the oscilloscope.

4-2 DA18000AC-OM-E Rev A

Figure 4-1. Vertical Menu

Operation

Control through the oscilloscope’s interface can be found in the screen menu of the channel
to which the amplifier is connected.

Touching the tab indicating the attached amplifier (in this case DA18000AC) will activate the
amplifier menu screen. Figure 4-5.

The amplifier information frame shows the characteristics of the amplifier only.

In some applications it may be desirable to turn the amplifier’s AutoColor ID OFF or ON with
touching the Led On frame.

Figure 4-2. Probe menu.

CONNECTING THE AMPLIFIER TO THE TEST CIRCUIT

For all modules and interconnect leads, positive voltages applied to the + input relative to
the – input will deflect the oscilloscope trace towards the top of the screen.

Type K Input Leads

The Type K Interconnect System has been designed to connect directly to female type K
connectors as well as to the higher performance 3.5 mm and 2.92 mm female connectors.

The Interconnect Lead connect to the amplifier and the matched pair of SMA Leads connect
to the Interconnect Lead.

The connector should be tightnened to a torque of 0.06 Nm (8 in.-oz.).

Note

The Type K Input Leads are supplied as a matched pair. Individual cables should
not be interchanged between amplifiers.

DA18000AC-OM-E Rev A 4-3

DA18000AC Differential Amplifier

USE OF DC ÷2 ATTENUATOR

The ÷2 attenuator should be used when the common mode or differential voltage of the cir­cuit under test is unknown or exceeds the maximum voltage specified. (See section 9, Spec­ifications). The use of the attenuator will also reduce the reflections, thus improving the
VSWR.

The DA18000AC amplifier has no method to detect the presence or absence of the attenua­tor. To maintain correct vertical scale factor and amplitude measurement results, you must
inform the oscilloscope when the attenuator is being used. This is done in the Vertical

Adjust → DA18000AC control dialog for the channel that the amplifier is connected to.

GROUNDING

In most cases, when the common mode portion of the signal consists mainly of lower fre­quencies, the amplifier does not need to be connected to ground of the circuit under test.
This will minimize the effects of ground loop currents. Any signal corruption caused by not
having the amplifier connected to ground of the signal under test will be common to both
inputs and will be rejected by the differential operation of the amplifier.

However when working in an environment with high RF ambient noise, it may be better to
connect the amplifier ground lead to a good RF ground near the point where the signal is
being measured. To find out if a ground lead is necessary, make a measurement with and
without a ground lead and use the one that gives the least signal corruption.

The cables attached to the DA18000AC amplifier are always grounded to the oscilloscope
and to earth ground through the power line cable.

DYNAMIC RANGE

The DA18000AC amplifier has no gain or attenuation control. The system gain is fixed at x1.

The DA18000AC amplifier is always AC coupled. However exceeding the common mode
range may introduce distortion to the output signal. Use of the ÷2 attenuators will increase
the differential mode range; however, due to power limitations, they will not increase the
common mode range.

There are two common mode voltages:

±10 V without a ÷2 attenuator
7 V

with a ÷2 attenuator

rms

###

4-4 DA18000AC-OM-E Rev A

Care and Maintenance

5Care and Maintenance

CLEANING

The exterior of the amplifier and cable should be cleaned using a soft cloth only moistened
with water or isopropyl alcohol. The use of abrasive agents, strong detergents or other sol­vents may damage the exterior of the amplifier.

CAUTION

The amplifier case is not sealed and should never be immersed in
any fluid.

SERVICE STRATEGY

Defective amplifiers must be returned to a LeCroy service facility for diagnosis and repair or
replacement. A defective product under warranty will be repaired or replaced.

RETURNING AN AMPLIFIER FOR CALIBRATION OR SERVICE

Procedure for returning a product for calibration or service:

Contact your local LeCroy sales representative to find out where to return the product. All
returned products should be identified by model number and serial number. Provide your
name and contact number and if possible describe the defect or failure. In case of products
returned to the factory, a Return Authorization Number (RAN) should be used. The RAN can
be established by contacting your nearest LeCroy sales office, representative, or the North
America Customer Care Center.

Return shipment should be prepaid. LeCroy cannot accept COD or Collect Return ship­ments. We recommend air-freighting.

Note

It is important that the RAN be clearly shown on the outside of the shipping package
for prompt redirection to the appropriate department.

1. Contact your local LeCroy sales or service representative to obtain a Return Authoriza­tion Number.

2. Remove all accessories from the amplifier. Do not include the manual. If you need to
return a DA18000AC system, do include all Interconnect Leads.

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:

•RAN

• Name and address of the owner

• Product 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.

DA18000AC-OM-E Rev A 5-1

DA18000AC Differential Amplifier

6. Mark the outside of the box with the shipping address given to you by the LeCroy rep­resentative; be sure to add the following:

• ATTN: <RAN assigned by the LeCroy representative>

•FRAGILE

7. Insure the item for the replacement cost of the product.

8. Ship the package to the appropriate address.

RETURNING AN AMPLIFIER TO A DIFFERENT COUNTRY

In order to avoid customs duty for purchase price of a new amplifier or accessory, when your
probe is returned for service, please use the following procedure.

In addition to the items mentioned above in ‘Returning a probe for calibration or service’,
you’ll need to 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 cost of the
service in the value column and the original value of the product at time of purchase 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.

REPLACEMENT PARTS

The amplifier accessories and other common parts can be ordered through the regional cus­tomer care centers. Refer to table 5-1 for LeCroy part numbers.

Table 5-1. Replaceable Parts List

Item LeCroy P/N

Type ‘K’ Lead PK18000-1 1

÷2 Attenuator 1

DA18000AC Instruction Manual DA18000AC-OM-E 1

###

Replacement

Quantity

5-2 DA18000AC-OM-E Rev A

Reference Information

6Reference Information

DIFFERENTIAL MODE AND COMMON MODE

Differential amplifiers sense the voltage difference which appears between the + input and –
input. This voltage is referred to as the Differential Mode or Normal Mode voltage. The volt­age component which is referenced to earth and is identical on both inputs is rejected by the
amplifier. This voltage is referred to as the Common Mode voltage and can be expressed as:

V

+input

--------------------------------------

=

V

CM

+

2

V

–input

DIFFERENTIAL MODE RANGE AND COMMON MODE RANGE

Differential Mode range is the maximum signal which can be applied between the + and ­inputs without overloading the amplifier/amplifier, which otherwise would result in clipping or
distorting of the waveform measured by the oscilloscope.

The Common Mode Range is the maximum voltage with respect to earth ground which can
be applied to either input. Exceeding the common mode range can result in unpredictable
measurements. Because the Common Mode signal is normally rejected and not displayed
on the oscilloscope, the user needs to be careful to avoid accidentally exceeding the com­mon mode range.

Because the input signal of a differential amplifier is not referenced to ground, the concept of
"V

" versus “V

peak

With a ground referenced signal, V
signal will have with respect to ground. In a differential system, there is no ground reference.

Therefore the Differential Mode Range refers to the maximum instantaneous amplitude of
the signal difference between the positive input and the negative input. Since most amplifi­ers have symmetrical bipolar inputs, the value is generally expressed as an absolute value,
and can have either polarity.

For example, an amplifier with a differential mode rating of ±1 V can have a maximum volt­age difference appearing at any instant in time of 1 V between the inputs. The polarity could
be either positive or negative. This does not imply that the number can be doubled to 2 volts,
however. For clarity, consider the following table of absolute voltages applied to the inputs of
a differential amplifier that has a differential mode range or ±1 V and a common mode range
of ±5 V:

” may be confusing.

peak-peak

is the maximum instantaneous voltage amplitude the

peak

DA18000AC-OM-E Rev A 6-1

DA18000AC Differential Amplifier

Voltage on +

input to ground

+1.5 V +0.8 V +0.7 V OK: within ±1 V

-1.5 V -0.8 V -0.7 V OK: within ±1 V

+0.8 V -0.1V +0.9 V OK: within ±1 V

+1.0 V -1.0 V +2.0 V Out of range:

+6.5 V +6.0 V 0.5 V Exceeds ±5 V

1.5 V

Some amplitudes are specified as "peak to peak." The differential amplifier peak-to-peak
range will be twice the peak differential mode range specification as, at any instant in time,
the maximum voltage amplitude signal would be one-half of the peak-to-peak value.

In a balanced differential system, the signal on each output will be an inverted copy of the
other input. For example, an LVDS system may have a pair of outputs, each of which has a
voltage swing of 0 to +370 mV. A logic 1 would be represented when the + output is at
+370 mV, while the - output is at 0 V. A logic zero would be the opposite polarity: the + output
at 0 V and the - output at +370 mV. Note that even though both outputs swing 370 mV, the
maximum difference voltage between them at any instant is still within ±370 mV. So this sig­nal could be measured with a differential amplifier that has a differential mode range of ±400
mV.

sine Ground 0.75 Vpeak OK: within ±1 V

pk-pk

Voltage on -

input to ground

Difference Comment

range

range

range

exceeds ±1 V

common mode

range

range

COMMON MODE REJECTION RATIO

The ideal differential amplifier/amplifier would sense and amplify only the differential mode
voltage component and reject all of the common mode voltage component. Real differential
amplifiers are not perfect and a small portion of the common mode voltage component
appears at the output. Common Mode Rejection Ratio (CMRR) is the measure of how much
the amplifier rejects the common mode voltage component. CMRR is equal to the differential
mode gain (or normal gain) divided by the common mode gain. Common mode gain is equal
to the output voltage divided by the input voltage when both inputs are driven by only the
common mode signal. CMRR can be expressed as a ratio (e.g. 10,000:1) or implicitly in dB
(e.g. 80 dB). Higher numbers indicate greater rejection (better performance).

The first order term which determines the CMRR is the relative gain matching between the +
and – input paths. To obtain high CMRR values, the input attenuators in a differential ampli­fier are precisely matched to each other. The matching includes the DC attenuation as well
as the capacitance which determines the AC attenuation. As the frequency of the common

6-2 DA18000AC-OM-E Rev A

Reference Information

mode component increases, the effects of stray parasitic capacitance and inductance in
determining the AC component becomes more pronounced. The CMRR becomes smaller
as the frequency increases. Hence the CMRR is usually specified in a graph of CMRR ver­sus common mode frequency.

The common mode frequency in these graphs is assumed to be sinusoidal. In real life appli­cations, the common mode signal is seldom a pure sine wave. Signals with pulse wave
shapes contain frequency components much higher than the repetition rate may suggests.
As such, it is very difficult to predict actual performance in the application for CMRR versus
frequency graphs. The practical application of these graphs is to compare the relative com­mon mode rejection performance between different probes and amplifiers.

###

DA18000AC-OM-E Rev A 6-3

DA18000AC Differential Amplifier

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6-4 DA18000AC-OM-E Rev A

Performance Verification

7Performance Verification

INTRODUCTION

This procedure can be used to verify the warranted characteristics of the DA18000AC Differ­ential Amplifier.

The recommended calibration interval for this amplifier is one year. Test results can be
recorded on a photocopy of the Test Record provided in Appendix A.

Performance Verification can be completed without removing any covers or exposing the
user to hazardous voltages. No adjustments are provided.

In the unlikely event that the amplifier should fail the performance verification, it can be sent
back to the local service center or the factory. For information on returning the amplifier refer
to Section 5, Care and Maintenance.

This procedure tests the DA18000AC for the following warranted specification:

•Rise time

TEST EQUIPMENT REQUIRED

Table 7-1 lists the test equipment and accessories, or their equivalents, that are required for
performance verification of the DA18000AC Differential Amplifier.

This procedure has been developed to minimize the number of parameters required to be
calibrated in the test instrumentation.

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.

Table 7-1. List of Required Equipment

Description Minimum Requirements

Test Equipment

Examples

Oscilloscope, High BW SDA 18000 LeCroy: SDA 18000

Step Generator, Differential Differential output with

deskew capability
T

≤ 20 ps

r

V

≈ 200 mV

out

LeCroy WaveExpert
oscilloscope with two ST­20 TDR sampling
modules

Attenuator, 2 ea. 6 dB, female-female, type K Supplied with

DA18000AC

Type K coaxial cable, 2 ea. male-male, type K, 50 Ω Supplied with DA1800AC

Connector Saver female-female, type K Supplied with ST-20

Torque Wrench 8 in.-lbs. LeCroy: TW-8

DA18000AC-OM-E Rev A 7-1

DA18000AC Differential Amplifier

PRELIMINARY PROCEDURE

1. Allow at least 20 minutes warm-up time for the DA18000AC Differential Amplifier and
test equipment before performing the Verification Procedure.

2. Turn on the other test equipment and allow these to warm up for the time recom­mended by the manufacturer.

3. While the instruments are reaching operating temperature, make a photocopy of the
Performance Verification Test Record (located in Appendix A), and fill in the necessary
data.

The warranted characteristics of the DA18000AC Differential Amplifier are valid at any tem­perature within the Environmental Characteristics listed in “Specifications.” However, some
of the other test equipment used to verify the performance may have environmental limita­tions required to meet the accuracy requirements needed for the procedure. Be sure that the
ambient conditions meet the requirements of all the test instruments used in the procedure.

VERIFICATION PROCEDURE

Rise Time (20-80%)

Measuring the amplifier’s rise time cannot be done directly, it has to be performed in an indi­rect way. First you have to measure the rise time of the source, i.e., the rise time of the pulse
generator (TDRs) and the oscilloscope. Second, measure the rise time of the system: pulse
generator, amplifier, and oscilloscope. The rise time of the amplifier alone can then be deter­mined from these two measurements.

ESD Sensitive: The inputs of the DA18000AC amplifier as well as
those of the oscilloscopes are sensitive to Electrostatic Discharge
(ESD). To avoid causing damage to the equipment, always follow anti-

CAUTION

a. Install the two ST-20 TDRs in Ch 1 and Ch 2 of the WE 9000 oscilloscope.

b. To prevent accidental discharge of any accumulated charge in the coaxial cables,

attach a ÷2 attenuator to one end of each of the two type K coaxial cables before con-
necting the cables to the oscilloscope. This will provide a discharge path.

c. Then connect the other end of each cable to the connector saver at the outputs of the

ST-20 TDRs.

static procedures (wear wrist strap, etc.) when working with these
instruments.

When fastening a SMA or type K connector, always use the torque
wrench to tighten the connector.

CAUTION

d. Remove the ÷2 attenuator from the coaxial cables.

e. From the menu bar, select Timebase (Figure 7-1).

f. Set the WE 9000 to output a differential step. This sampling oscilloscope is only used

to provide power to the ST-20 TDR pulse generators

g. Initialize the TDR by touching the TDR Main tab.

7-2 DA18000AC-OM-E Rev A

Performance Verification

Figure 7-1. Timebase Menu

h. Connect the ST-20 TDR coaxial cable from Channel 1 of the WE 9000 via the LPA–K

adapter to Channel 1 of the SDA 18000. Be sure to properly torque all connectors
(8 in.-lbs.).

i. Set the SDA 18000 to Channel 1 and the timebase to 500 ps/div and 60 GS/s. Set the

scope to trigger on Channel 1, and edge triggering to positive slope.

j. Set math trace F1 to the Ptrace mean of Channel 1 (Figure 7-2).

DA18000AC-OM-E Rev A 7-3

DA18000AC Differential Amplifier

Figure 7-2. Math Menu Setup

k. Set a measurement function to measure Rise 20-80% (Figure 7-3).

7-4 DA18000AC-OM-E Rev A

Figure 7-3. Measure Menu Setup

Performance Verification

l. Record the measured 20-80% rise time as “Source rise time” (t

Record (Figure 7-4).

Only the positive edge is measured. The difference in rise time between the positive
edge and the negative edge of the STD-20 TDR is less than 1 ps.

m. To measure the amplifier’s rise time, disconnect the coaxial cable and PLPA-K adapter

from Channel 1 of the SDA 18000 and connect the cable only to the + input of the
DA18000AC amplifier. Connect the cable from Channel 2 TDR to the – input of the
amplifier.

n. Measure the 20-80% rise time and record the measurement as “System rise time”

(t

) in the Test Record.

system

o. Calculate the amplifier’s rise time:

source

) in the Test

Amplifier Rise Time, t

r

t

()2t

system

–=

()

2

source

Figure 7-4Rise Time Measurement

p. Record the calculated rise time as “Amplifier Rise Time” in the Test Record.

q. Verify that the calculated rise time for the DA18000AC is less than 19 ps.

This concludes the Performance Verification Procedure.

###

DA18000AC-OM-E Rev A 7-5

DA18000AC Differential Amplifier

BLANK PAGE

7-6 DA18000AC-OM-E Rev A

Specifications

8Specifications

The specifications are valid for probes when the following conditions have been met:

• The probe has been operating for at least 30 minutes in an environment, which is
within the operating environmental specifications.

• The probe has been calibrated within the last 12 months. Calibration was performed
in a controlled environment of 25 °C ±5 °C.

NOMINAL CHARACTERISTICS

Nominal characteristics describe parameters and attributes that are guaranteed by design,
but do not have associated tolerances.

General

Input Configuration True differential, + and – Inputs

Input Connectors Type K (2.92 mm)

The type K input leads will connect directly to
female type K connectors on the system under
test.

Maximum Non-Destruct

Input Voltage, continuous 10 V

Amplifier Gain ~ 1.2

Oscilloscope display factor is calibrated to actual amplifier gain

Input Impedance 100 Ω, true differential

Max Input: Differential Mode

Without ÷2 attenuators ±400 mV, 800 mV

With ÷2 attenuators ±800 mV, 1.6 V

Max Input: Common Mode

Without ÷2 attenuators 10 mV

With ÷2 attenuators 7 V

peak

p-p

p-p

p-p

rms

WARRANTED CHARACTERISTICS

Warranted characteristics describe parameters that have guaranteed performance. Unless
otherwise noted, tests are provided in Section 8, Performance Verification, for all warranted
specifications.

Rise Time (Amplifier only)

1. Measured with an SDA 18000 oscilloscope. Rise time of oscilloscope and source sub-

tracted (rms).

DA18000AC-OM-E Rev A 8-1

(20-80%)

1

19 ps

DA18000AC Differential Amplifier

TYPICAL CHARACTERISTICS

Typical characteristics are parameters with no guaranteed performance. Tests for typical
characteristics are not provided in the Performance Verification Procedure.

1

Bandwidth (System)

Rise Time (System)

(20-80%)

Propagation Delay 7.3 ns

Gain Variation with Temperature 0.1% / °C

Noise, System

Noise, Amplifier only 0.5 V

CMRR

100 kHz to 18 GHz > 16 dB (See Figure 8-1.)

Input Match Differential Mode

Without ÷2 attenuators –14 dB (VSWR 1.5:1)

With ÷2 attenuators –19 dB (VSWR 1.25:1)

Input Match Common Mode

Without ÷2 attenuators –6 dB (VSWR 3:1)

With ÷2 attenuators –12 dB (VSWR 1.7:1)

Total Harmonic Distortion 2.5% (at maximum input)

(Amplifier only)

100 kHz to 18 GHz

(with SDA 18000)

2

< 24 ps

3

1 mV

(Referred to amplifier input)

rms

rms

1. Measured with an swept sine wave source or step with FFT. Frequency of oscilloscope
channel subtracted from the measurement.

2. Measured with an SDA 18000 oscilloscope. Step optimized for eye diagram.

3. Measured with an SDA 18000 oscilloscope using SDEV function to remove offset.

8-2 DA18000AC-OM-E Rev A

Figure 8-1. Typical DA18000AC CMRR

Specifications

ENVIRONMENTAL CHARACTERISTICS

The Environmental Characteristics are tested to specification MIL-PRF-28800F Class 4

Temperature (Operating) 0 °C to 40 °C

Temperature (Non-operating) -40 °C to 71 °C

Humidity (Operating) 5% to 80% RH (Non-condensing)

50% RH above 30 °C

Humidity (Non-operating) 5% to 95% RH (Non-condensing)

75% RH above 30 °C and 45% RH above 40 °C

PHYSICAL CHARACTERISTICS

Cable Length 1.3 m (4 ft. 3 in)

Weight:

Amplifier only 385 g (13.5 oz.)

Shipping 1.36 kg (3 lbs. 0 oz)

DA18000AC-OM-E Rev A 8-3

DA18000AC Differential Amplifier

COMPLIANCE AND CERTIFICATIONS

CE Compliant

EC Declaration of Conformity

The DA18000AC meets the intent of the European Council Directive 73/23/EEC for Product
Safety and 89/336/EEC for Electromagnetic Compatibility. This declaration is based upon
compliance of the product to the following standards:

Low Voltage Directive: EN 61010-031:2002

EMC Directive: EN 61326/A3:2003

Caution

This is a Class A product. In a domestic environment this product may cause radio
interference, in which case the user may be required to take appropriate measures.

Safety requirements for electrical equipment for mea­surement, control and laboratory use.
Part 031: Safety requirements for hand-held probe
assemblies
for electrical measurements and test.

EMC requirements for electrical equipment for measure­ment, control and laboratory use.

EN 55011/A2:2001 Radiated Emissions (Class A)

EN 61000-4-2:1995+Amd2:2001
Discharge Immunity (±4 kV contact discharge, ±8
kV air discharge)

EN 61000-4-3/A1:2003
netic Field Immunity (3 V/m, 30 MHz to 1 GHz,
80% amplitude modulated with 1 kHz sine wave)

###

1

RF Radiated Electromag-

1

Electrostatic

1. Meets Performance Criteria “B” limits – temporary, self-recoverable degradation or loss of
performance is allowed, but no change of actual operating state or loss of stored data is
allowed.

8-4 DA18000AC-OM-E Rev A

Appendix A

AAppendix A

PERFORMANCE VERIFICATION TEST RECORD

This record can be used to record the results of measurements made during the perfor­mance verification of the DA18000AC Differential Amplifier.

Photocopy this 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.

ITEMS TESTED

Item Serial Number

DA18000AC

EQUIPMENT USED:

Model Serial Number

Calibration Due

Date

OSCILLOSCOPE

OSCILLOSCOPE

ST-20 TDR

ST-20 TDR

TEST RECORD

Step Description Intermediate data Test Result

Rise Time

1-m Source rise time, t

1-o System rise time, t

1-q Probe Rise Time, t

DA18000AC-OM-E Rev A A-1

source

system

(< 19 ps) _________ ps

r

______________ ps

______________ ps

###

DA18000AC Differential Amplifier

BLANK PAGE

A-2 DA18000AC-OM-E Rev A