Keysight Technologies N4985A-P15, N4985A-P25, N4985A-S30, N4985A-S50 Operating And Service Manual

Keysight N4985A
System Amplifiers

Operating and
Service Manual

Notices

CAUTION

WARNING

Copyright Notice

© Keysight Technologies 2013-2017
No part of this manual may be repro-

duced in any form or by any means
(including electronic storage and
retrieval or translation into a foreign
language) without prior agreement and
written consent from Keysight Technol­ogies as governed by United States and
international copyright laws.

Manual Part Number

N4985-90001

Edition

Edition 3, March 17, 2017

Printed in:

Printed in Malaysia

Published by:

Keysight Technologies
Bayan Lepas Free Industrial Zone,
11900 Penang, Malaysia

Technology Licenses

The hard ware and/or software
described in this document are fur­nished under a license and may be
used or copied only in accordance with
the terms of such license.

Declaration of Conformity

Declarations of Conformity for this
product and for other Keysight prod­ucts may be downloaded from the
Web. Go to http://www.keysight.com/

go/conformity. You can then search by

product number to find the latest Dec­laration of Conformity.

U.S. Government Rights

The Software is “commercial computer
software,” as defined by Federal Acqui­sition Regulation (“FAR”) 2.101. Pursu­ant to FAR 12.212 and 27.405-3 and
Department of Defense FAR Supple­ment (“DFARS”) 227.7202, the U.S.
government acquires commercial com­puter software under the same terms
by which the software is customarily
provided to the public. Accordingly,
Keysight provides the Software to U.S.
government customers under its stan­dard commercial license, which is
embodied in its End User License
Agreement (EULA), a copy of which can
be found at http://www.keysight.com/

find/sweula. The license set forth in the

EULA represents the exclusive authority
by which the U.S. government may use,
modify, distribute, or disclose the Soft­ware. The EULA and the license set
forth therein, does not require or per­mit, among other things, that Keysight:
(1) Furnish technical information
related to commercial computer soft­ware or commercial computer software
documentation that is not customarily
provided to the public; or (2) Relinquish
to, or otherwise provide, the govern­ment rights in excess of these rights
customarily provided to the public to
use, modify, reproduce, release, per­form, display, or disclose commercial
computer software or commercial com­puter software documentation. No
additional government requirements
beyond those set forth in the EULA
shall apply, except to the extent that
those terms, rights, or licenses are
explicitly required from all providers of
commercial computer software pursu­ant to the FAR and the DFARS and are
set forth specifically in writing else­where in the EULA. Keysight shall be
under no obligation to update, revise or
otherwise modify the Software. With
respect to any technical data as
defined by FAR 2.101, pursuant to FAR

12.211 and 27.404.2 and DFARS

227.7102, the U.S. government
acquires no greater than Limited Rights
as defined in FAR 27.401 or DFAR

227.7103-5 (c), as applicable in any
technical data.

Warranty

THE MATERIAL CONTAINED IN THIS
DOCUMENT IS PROVIDED “AS IS,”
AND IS SUBJECT TO BEING
CHANGED, WITHOUT NOTICE, IN
FUTURE EDITIONS. FURTHER, TO THE
MAXIMUM EXTENT PERMITTED BY
APPLICABLE LAW, KEYSIGHT DIS­CLAIMS ALL WARRANTIES, EITHER
EXPRESS OR IMPLIED, WITH REGARD
TO THIS MANUAL AND ANY INFORMA­TION CONTAINED HEREIN, INCLUD­ING BUT NOT LIMITED TO THE
IMPLIED WARRANTIES OF MER­CHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE. KEYSIGHT
SHALL NOT BE LIABLE FOR ERRORS
OR FOR INCIDENTAL OR CONSE­QUENTIAL DAMAGES IN CONNECTION
WITH THE FURNISHING, USE, OR
PERFORMANCE OF THIS DOCUMENT
OR OF ANY INFORMATION CON­TAINED HEREIN. SHOULD KEYSIGHT
AND THE USER HAVE A SEPARATE
WRITTEN AGREEMENT WITH WAR­RANTY TERMS COVERING THE MATE­RIAL IN THIS DOCUMENT THAT
CONFLICT WITH THESE TERMS, THE
WARRANTY TERMS IN THE SEPARATE
AGREEMENT SHALL CONTROL.

Safety Information

A CAUTION notice denotes a hazard. It
calls attention to an operating proce­dure, practice, or the like that, if not
correctly performed or adhered to,
could result in damage to the product
or loss of important data. Do not pro­ceed beyond a CAUTION notice until
the indicated conditions are fully
understood and met.

A WARNING notice denotes a hazard. It
calls attention to an operating proce­dure, practice, or the like that, if not
correctly performed or adhered to,
could result in personal injury or death.
Do not proceed beyond a WARNING
notice until the indicated conditions are
fully understood and met.

2 Keysight N4985A Operating and Service Manual

Compliance Notices and Regulatory Information

Compliance with Electromagnetic Compatibility (EMC)

This product conforms with the protection requirements of EMC Directive 2004/
108/EC for Electromagnetic Compatibility.

This product complies to the EMC Directive by assessment according to the IEC/
EN61326-1:2005 EMC standard.

In order to preserve the EMC performance of this product, any cable which
becomes worn or damaged must be replaced with the same type and
specifications.

Keysight N4985A Operating and Service Manual 3

Regulatory markings

The CE mark is a registered trademark of the
European Community. This CE mark shows that
the product complies with all the relevant
European Legal Directives.

The RCM mark is a registered trademark of the
Australian Communications and Media Authority.

The CE mark is a registered
trademark of the European
Community. This CE mark shows
that the product complies with
all the relevant European Legal
Directives.

ICES/NMB-001 indicates that
this ISM device complies with
the
Canadian ICES-001.
Cet appareil ISM est conforme a
la norme NMB-001 du Canada.

ISM GRP.1 Class A indicates that
this is an Industrial Scientific and
Medical Group 1 Class A
product.

This symbol indicates the time
period during which no
hazardous or toxic substance
elements are expected to leak or
deteriorate during normal use.
Forty years is the expected useful
life of the product.

South Korean Class A EMC declaration:

This equipment is Class A suitable for
professional use and is for use in electromagnetic
environments outside of the home.

This instrument complies with
the WEEE Directive (2002/96/
EC) marking requirement. This
affixed product label indicates
that you must not discard this
electrical or electronic product in
domestic household waste.

4 Keysight N4985A Operating and Service Manual

Waste Electrical and Electronic Equipment (WEEE) Directive 2002/
96/EC

This instrument complies with the WEEE Directive (2002/96/EC) marking
requirement. This affixed product label indicates that you must not discard this
electrical or electronic product in domestic household waste.

Product category

With reference to the equipment types in the WEEE directive Annex 1, this
instrument is classified as a “Monitoring and Control Instrument” product.

The affixed product label is as shown below.

Do not dispose in domestic household waste.

To return this unwanted instrument, contact your nearest Keysight Service Center,
or visit http://about.keysight.com/en/companyinfo/environment/takeback.shtml
for more information.

Sales and Technical Support

To contact Keysight for sales and technical support, refer to the support links on
the following Keysight websites:

– www.keysight.com/find/mta

(product-specific information and support, software and
documentation updates)

– www.keysight.com/find/assist

(worldwide contact information for repair and service)

Keysight N4985A Operating and Service Manual 5

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6 Keysight N4985A Operating and Service Manual

Table of Contents

Compliance Notices and Regulatory Information . . . . . . . . . . . . . . . . . . 3

Compliance with Electromagnetic Compatibility (EMC) . . . . . . . . . . .3

Regulatory markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Waste Electrical and Electronic Equipment (WEEE) Directive 2002/96/

EC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Product category . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Sales and Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

1Introduction

Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Features of the Keysight N4985A amplifiers . . . . . . . . . . . . . . . . . . .16

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

2Installation

Initial Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Service and Recalibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Related Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Operating and Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

ESD damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Connector care . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

3 Specifications

General Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Supplementary Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Physical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Mechanical Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

4Operating Guide

Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

Performance verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

Keysight N4985A Operating and Service Manual 7

Example Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Service and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

8 Keysight N4985A Operating and Service Manual

List of Figures

Figure 1-1 Keysight N4985A-S30/N4985A-S50 amplifier . . . . . .14

Figure 1-2 Keysight N4985A-P15/N4985A-P25 amplifier . . . . . .15

Figure 3-1 Small signal parameters versus frequency (for

Figure 3-2 Gain versus output power (P

Figure 3-3 Saturated output power (for N4985A-S30) . . . . . . . . .28

Figure 3-4 N4985A-OA3 (2
Figure 3-5 N4985A-OA3 (2

Figure 3-6 N4985A-OA3 (2
Figure 3-7 N4985A-OA3 (2

Figure 3-8 Small signal parameters versus frequency (for

Figure 3-9 Gain versus output power (P

Figure 3-10 Saturated output power (for N4985A-S50) . . . . . . . . .32

Figure 3-11 Input pulse = Ch3, 420 m Vppk, 10.4 pS rise time, Output

Figure 3-12 N4985A-OA5 (2
Figure 3-13 N4985A-OA5 (2

Figure 3-14 N4985A-OA5 (2
Figure 3-15 N4985A-OA5 (2

Figure 3-16 Typical N4985A-P15 performance (S21) . . . . . . . . . . .37

Figure 3-17 Typical N4985A-P15 performance (group delay) . . . .37

Figure 3-18 Typical N4985A-P15 performance (S11, S22) . . . . . .38

Figure 3-19 Typical N4985A-P15 performance (saturated output

Figure 3-20 Typical N4985A-P25 performance (S21) . . . . . . . . . . .39

Figure 3-21 Typical N4985A-P25 performance (group delay) . . . .39

N4985A-S30) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

indicated with *) [for

1dB

N4985A-S30] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

31

– 1) EYE: >7 V output (1.5 V/div) . .29

31

– 1) EYE: <500 fs added rms jitter (5 ps/

div) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

31

– 1) EYE: <10 ps Tf/Tf (5 ps/div) . . 30

31

– 1) EYE: Input signal from PRBS

generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

N4985A-S50) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

indicated with *) [for

1dB

N4985A-S50] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

pulse = Ch4, 6.5 Vppk, 11.0 pS rise time (for

N4985A-S50) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

31

– 1) EYE: >7 V output (1.5 V/div) . .33

31

– 1) EYE: <500 fs added rms jitter (5 ps/

div) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

31

– 1) EYE: <10 ps Tf/Tf (5 ps/div) . . 34

31

– 1) EYE: Input signal from PRBS

generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

power) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

Keysight N4985A Operating and Service Manual 9

Figure 3-22 Typical N4985A-P25 performance (S11, S22) . . . . . . 40

Figure 3-23 Typical N4985A-P25 performance (saturated output

power) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Figure 3-24 Mechanical dimensions of the N4985A-S30/N4985A-S50

amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Figure 3-25 Mechanical dimensions of the N4985A-P15/N4985A-P25

amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Figure 4-1 Verification setup with a power splitter . . . . . . . . . . . 46

Figure 4-2 Verification setup with a calibrated coupler . . . . . . . . 46

Figure 4-3 Example of an amplified RF power measurement system

47

10 Keysight N4985A Operating and Service Manual

List of Tables

Table 3-1 N4985A-S30 and N4985A-S50 specifications . . . . . .26

Table 3-2 Additional specifications for N4985A-OA3 . . . . . . . . .27

Table 3-3 Additional specifications for N4985A-OA5 . . . . . . . . .27

Table 3-4 N4985A-P15 and N4985A-P25 specifications . . . . . .35

Table 3-5 Supplementary specifications for the N4985A amplifiers

41

Table 3-6 Physical specifications for the N4985A amplifiers . . .41

Keysight N4985A Operating and Service Manual 11

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12 Keysight N4985A Operating and Service Manual

Keysight N4985A System Amplifiers
Operating and Service Manual

1 Introduction

Product Overview 14

This chapter provides an overview of the N4985A system amplifiers.

13

1Introduction

N4985A-S30 amplifier

N4985A-S50 amplifier

Product Overview

High performance broadband RF amplifier

The N4985A-S30 and N4985A-S50 system amplifiers are high performance,
broadband amplifiers featuring baseband RF (<100 kHz) through millimeter wave
frequency coverage. These amplifiers, which have many uses in research,
development, or production-line environment, are a useful addition to the
laboratory where RF, microwave, or millimeter wave measurements are made.
Typical applications include:

– RF source amplifier.

– Mixer LO amplifier.

– Noise figure LNA and noise figure system amplifier.

– Pulse amplifier and time domain applications.

– Digital communication systems.

– Antenna research and development.

– General purpose RF gain block.

Figure 1-1 Keysight N4985A-S30/N4985A-S50 amplifier

14 Keysight N4985A Operating and Service Manual

Introduction 1

N4985A-P15 amplifier

N4985A-P25 amplifier

High performance system amplifier

The N4985A-P15 and N4985A-P25 are high performance, broadband amplifiers
with excellent power and gain up to 50 GHz, which have many uses in research,
development, or production-line environment. These amplifiers are a useful
addition to the laboratory where RF, microwave, or millimeter wave
measurements are made. Typical applications include:

– Driver for high power amplifiers such as TWT or linear power amplifiers.

– Overcome system losses such as long transmission lines, power dividers, etc.

– Antenna research and development; antenna characterization systems.

– Broadband RF characterization.

Figure 1-2 Keysight N4985A-P15/N4985A-P25 amplifier

Keysight N4985A Operating and Service Manual 15

1Introduction

Features of the Keysight N4985A amplifiers

The N4985A is a high performance amplifier featuring broadband frequency
coverage.

Model Frequency range Gain

N4985A-S30 100 kHz to 30 GHz 30 dB

N4985A-S50 100 kHz to 50 GHz 30 dB

N4985A-P15 10 MHz to 50 GHz 25 dB

N4985A-P25 2 GHz to 50 GHz 27 dB

N4985A-S30 and N4985A-S50

– The amplifier is designed to be a multi-use laboratory RF amplifier as a gain

block for frequency domain applications or as a time domain pulse amplifier.

– The amplifier’s small size and versatile performance make it an excellent

selection as a general purpose gain block with moderate power output in a
single package potentially replacing two or three narrower band amplifiers.

N4985A-P15 and N4985A-P25

– The amplifier is designed to be easily used in laboratory and test applications.

– It is small in size and has built-in bias power supplies allowing close

placement to the measurement or source reference plane. Its high gain helps
to compensate for system losses such as long transmission lines and system
components.

16 Keysight N4985A Operating and Service Manual

Applications

The N4985A-S30 and N4985A-S50 system amplifiers are an often needed
companion to synthesized signal generators and microwave sources. The small
size of the amplifiers allows close placement to the DUT or test fixture. High gain
and greater than 20 dBm output power will overcome long cable losses from the
signal source and provide the additional output power needed in many
development and test applications.

The N4985A-P15 and N4985A-P25 are test amplifiers designed for broadband
power and gain applications. It is ideally suited for saturated RF amplifier testing,
driving TWT amplifiers, or as an antenna system amplifier. High gain and typically
22 dBm output power at 50 GHz will overcome long cable losses from the signal
source, and will provide additional power required in many development and test
applications.

Introduction 1

Keysight N4985A Operating and Service Manual 17

1Introduction

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18 Keysight N4985A Operating and Service Manual

Keysight N4985A System Amplifiers
Operating and Service Manual

2 Installation

Initial Inspection 20
Service and Recalibration 21
Related Documentation 21
Operating and Safety Precautions 22

This chapter provides you important information on how to check and prepare
your instrument for operation.

19

2Installation

Initial Inspection

1 Unpack and inspect the shipping container and its contents thoroughly to

ensure that nothing was damaged during shipment. If the shipping container
or cushioning material is damaged, the contents should be checked both
mechanically and electrically. Check for mechanical damage such as
scratches or dents. Procedures for checking electrical performance are given
under “Performance verification” on page 46.

2 If the contents are damage or defective, contact your nearest Keysight

Technologies Service and Support office. Refer to “Sales and Technical

Support” on page 5 of this manual. Keysight Technologies will arrange for

repair or replacement of the damaged or defective equipment. Keep the
shipping materials for the carrier’s inspection.

3 If you are returning the instrument under warranty or for service, repackaging

the instrument requires original shipping containers and materials or their
equivalents. Keysight Technologies can provide packaging materials identical
to the original materials. Refer to “Sales and Technical Support” on page 5 of
this manual for the Keysight Technologies nearest to you. Attach a tag
indicating the type of service required, return address, model number, and
serial number. Mark the container FRAGILE to insure careful handling. In any
correspondence, refer to the instrument by model number and serial number.

20 Keysight N4985A Operating and Service Manual

Service and Recalibration

If your N4985A amplifiers require service or repair, contact the nearest Keysight
office for information on where to send it. Refer to “Sales and Technical Support”
on page 5 of this manual. The performance of the N4985A can only be verified by
specially-manufactured equipment and calibration standards from Keysight. The
recommended interval for recalibration is 12 months.

Related Documentation

This Operating and Service Manual is shipped with the product. It is also available
at www.keysight.com/find/mta.

Installation 2

Keysight N4985A Operating and Service Manual 21

2Installation

Operating and Safety

Observe the following guidelines before connecting or operating the N4985A
system amplifiers.

ESD damage

Protection against electrostatic discharge (ESD) is important while handling and
operating the N4985A.

Static electricity can build up on your body and can easily damage sensitive
components when discharged.

Static discharges too small to be felt can cause permanent damage to the unit.

To prevent damage from ESD:

– Use a grounded antistatic mat in front of your test equipment and wear a

grounded wrist strap attached to it when handling or operating the N4985A.

– Wear a heel strap when working in an area with a conductive floor.

– Ground yourself before you clean, inspect, or make a connection to the

N4985A. You can, for example, grasp the grounded outer shell of the analyzer
test port or cable connector briefly.

Precautions

– Avoid touching the exposed connector pins.

Connector care

Because connectors can become defective due to wear during normal use, all
connectors should be inspected and maintained to maximize their service life.

– Inspect the mating surface each time a connection is made. Metal particles

from connector threads often find their way onto the mating surface when a
connection is made or disconnected.

– Clean dirt and contamination from the connector mating surface and threads.

This simple step can extend the service life of the connector and improve the
quality of your calibration and measurements.

– Gage connectors periodically. This not only provides assurance of proper

mechanical tolerances and thus connector performance, but can also indicate
situations where the potential for damage to another connector may exist.

22 Keysight N4985A Operating and Service Manual

Installation 2

CAUTION

The N4985A can be damaged if excessive torque is applied to the
connectors.

The recommended torque value is 8 lb-in torque for 2.4 mm and 2.92 mm,
5 Ib-in torque for 1.85 mm DCA sampling head.

Keysight N4985A Operating and Service Manual 23

2Installation

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24 Keysight N4985A Operating and Service Manual

Keysight N4985A System Amplifiers
Operating and Service Manual

3 Specifications

General Specifications 26
Supplementary Specifications 41
Physical Specifications 41
Mechanical Dimensions 42

This chapter provides the specifications of the N4985A system amplifiers.

25

3 Specifications

General Specifications

Specifications

Specifications refer to the performance standards or limits against which the
N4985A is tested.

Typical characteristics are included for additional information only and they are
not specifications. These are denoted as “typical”, “nominal”, or “approximate” and
are printed in italics.

Table 3-1 N4985A-S30 and N4985A-S50 specifications

Specification N4985A-S30 N4985A-S50

Frequency 100 kHz to 30 GHz 100 kHz to 50 GHz

Gain (dB) 30 dB 30 dB

Small signal gain 27 (min), 30 (typ) 1 GHz to 26 GHz

Output power (at P

Input match S

Output match S

) (dB)

sat

(dB)

11

(dB)

22

20 (min), 22 (typ)

100 kHz to 26 GHz

–10 (typ) 1 GHz to 26 GHz

–10 (typ) 1 GHz to 26 GHz

Noise figure (dBm) 5 (typ) 2 GHz to 30 GHz

2nd harmonics H

(dBc) @P

2

1

–30 (typ) 2 GHz to 25 GHz –30 (typ) 2 GHz to 25 GHz

27 (min), 30 (typ)
24 (min), 27 (typ)

20 (min), 22 (typ)

20 (typ)
17 (typ)

–10 (typ)

–8 (typ)

–10 (typ)

–8 (typ)

5 (typ)
6 (typ)

1 GHz to 26 GHz

26 GHz to 45 GHz

100 kHz to 26 GHz

26 GHz to 40 GHz
40 GHz to 50 GHz

1 GHz to 26 GHz

26 GHz to 45 GHz

1 GHz to 26 GHz

26 GHz to 45 GHz

2 GHz to 3 GHz

30 GHz to 40 GHz

26 Keysight N4985A Operating and Service Manual

Specifications 3

Table 3-2 Additional specifications for N4985A-OA3

Description Minimum Typical Maximum

Output eye amplitude 7 7.5 —

S21 (V)

Input eye amplitude — 0.5 —

S21 (ps) Jitter additive (rms) — < 0.5 < 1

Tr/Tf (ps) Rise/fall time — < 8 < 10

Table 3-3 Additional specifications for N4985A-OA5

Description Minimum Typical Maximum

Output eye amplitude 7 7.5 —

S21 (V)

Input eye amplitude — 0.5 —

S21 (ps) Jitter additive (rms) — < 0.5 < 1

Tr/Tf (ps) Rise/fall time — < 8 < 10

Figure 3-1 Small signal parameters versus frequency (for N4985A-S30)

Keysight N4985A Operating and Service Manual 27

3 Specifications

Figure 3-2 Gain versus output power (P

indicated with *) [for

1dB

N4985A-S30]

Figure 3-3 Saturated output power (for N4985A-S30)

28 Keysight N4985A Operating and Service Manual

Figure 3-4 N4985A-OA3 (2

Specifications 3

31

– 1) EYE: >7 V output (1.5 V/div)

Figure 3-5 N4985A-OA3 (2

Keysight N4985A Operating and Service Manual 29

31

– 1) EYE: <500 fs added rms jitter (5 ps/div)

3 Specifications

Figure 3-6 N4985A-OA3 (2

31

– 1) EYE: <10 ps Tf/Tf (5 ps/div)

Figure 3-7 N4985A-OA3 (2

30 Keysight N4985A Operating and Service Manual

31

– 1) EYE: Input signal from PRBS generator

Specifications 3

Figure 3-8 Small signal parameters versus frequency (for N4985A-S50)

Figure 3-9 Gain versus output power (P

Keysight N4985A Operating and Service Manual 31

N4985A-S50]

indicated with *) [for

1dB

3 Specifications

Figure 3-10 Saturated output power (for N4985A-S50)

Figure 3-11 Input pulse = Ch3, 420 m Vppk, 10.4 pS rise time, Output pulse

32 Keysight N4985A Operating and Service Manual

= Ch4, 6.5 Vppk, 11.0 pS rise time (for N4985A-S50)

Figure 3-12 N4985A-OA5 (2

Specifications 3

31

– 1) EYE: >7 V output (1.5 V/div)

Figure 3-13 N4985A-OA5 (2

Keysight N4985A Operating and Service Manual 33

31

– 1) EYE: <500 fs added rms jitter (5 ps/div)

3 Specifications

Figure 3-14 N4985A-OA5 (2

31

– 1) EYE: <10 ps Tf/Tf (5 ps/div)

Figure 3-15 N4985A-OA5 (2

34 Keysight N4985A Operating and Service Manual

31

– 1) EYE: Input signal from PRBS generator

Specifications 3

Tab le 3-4 N4985A-P15 and N4985A-P25 specifications

Specification N4985A-P15 N4985A-P25

Frequency 10 MHz to 50 GHz 2 GHz to 50 GHz

Gain (dB) 30 dB 30 dB

Small signal gain

Output power (at P

Output power (at P

Input match S

(dB)

11

sat

1dB

) (dB)

) (dB)

20 (min), 25 (typ)
25 (min), 29 (typ)

24 (min), 28 (typ)
21 (min), 25 (typ)
17 (min), 24 (typ)

20 (min), 24 (typ)

26 (min), 30 (typ)

25 (min), 29 (typ)

23 (min), 27 (typ)
20 (min), 24 (typ)

17 (min), 22 (typ)

24 (min), 28 (typ)
23 (min), 27 (typ)
21 (min), 25 (typ)
17 (min), 22 (typ)

–15 (typ)
–15 (typ)
–15 (typ)

–10 (typ)

–8 (typ)

10 MHz to 2 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

10 MHz to 2 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

10 MHz to 2 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

10 MHz to 2 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

25 (min), 29 (typ)
24 (min), 28 (typ)
21 (min), 25 (typ)
17 (min), 24 (typ)

26 (min), 30 (typ)
25 (min), 29 (typ)
23 (min), 27 (typ)
20 (min), 24 (typ)

24 (min), 28 (typ)
23 (min), 27 (typ)
21 (min), 25 (typ)
17 (min), 22 (typ)

–15 (typ)
–15 (typ)
–10 (typ)

–8 (typ)

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

Output match S

(dB)

22

Keysight N4985A Operating and Service Manual 35

–6 (typ)
–15 (typ)
–10 (typ)

–6 (typ)

–6 (typ)

10 MHz to 2 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

–15 (typ)
–10 (typ)

–6 (typ)
–6 (typ)

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

3 Specifications

Table 3-4 N4985A-P15 and N4985A-P25 specifications (continued)

Specification N4985A-P15 N4985A-P25

Reverse isolation (dB)

Noise figure (dBm)

2nd harmonics H

3rd harmonics H

(dBc) @P

2

(dBc) @P

3

–60 (typ)

–60 (typ)
–60 (typ)

–50 (typ)

–50 (typ)

9 (typ)
9 (typ)

10.5 (typ)
12 (typ)

–40 (typ)
–40 (typ)

1

–40 (typ)

–35 (typ)

–30 (typ)

–20 (typ)
–20 (typ)

1

–20 (typ)

—

—

10 MHz to 2 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

10 MHz to 2 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

10 MHz to 2 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

–60 (typ)
–60 (typ)
–50 (typ)
–50 (typ)

9 (typ)
9 (typ)

10.5 (typ)
12 (typ)

–40 (typ)
–40 (typ)
–35 (typ)
–30 (typ)

–20 (typ)
–20 (typ)

—
—

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

2 GHz to 10 GHz
10 GHz to 30 GHz
30 GHz to 40 GHz
40 GHz to 50 GHz

36 Keysight N4985A Operating and Service Manual

Figure 3-16 Typical N4985A-P15 performance (S21)

Specifications 3

Figure 3-17 Typical N4985A-P15 performance (group delay)

Keysight N4985A Operating and Service Manual 37

3 Specifications

Figure 3-18 Typical N4985A-P15 performance (S11, S22)

Figure 3-19 Typical N4985A-P15 performance (saturated output power)

38 Keysight N4985A Operating and Service Manual

Figure 3-20 Typical N4985A-P25 performance (S21)

Specifications 3

Figure 3-21 Typical N4985A-P25 performance (group delay)

Keysight N4985A Operating and Service Manual 39

3 Specifications

Figure 3-22 Typical N4985A-P25 performance (S11, S22)

Figure 3-23 Typical N4985A-P25 performance (saturated output power)

40 Keysight N4985A Operating and Service Manual

Supplementary Specifications

Specifications 3

Table 3-5 Supplementary specifications for the N4985A amplifiers

Model N4985A-S30 N4985A-S50 N4985A-P15 N4985A-P25

Bias voltage and current 9 Vdc at 500 mA 9 Vdc at 500 mA 9 Vdc at 1.5 A 9 Vdc at 1.5 A

RF connectors 2.92 mm (f) 2.4 mm (f) 2.4 mm (f) 2.4 mm (f)

Survival input power 20 dBm 20 dBm 26 dBm 26 dBm

Operating temperature 0 to +55 °C 0 to +55 °C 0 to +55 °C 0 to +55 °C

[a] Including the power supply and the DC power supply cable.

Physical Specifications

Table 3-6 Physical specifications for the N4985A amplifiers

Model N4985A-S30 N4985A-S50 N4985A-P15 N4985A-P25

Net weight 0.26 kg 0.26 kg 1.03 kg 1.03 kg

Shipping weight 1.8 kg 1.8 kg 3.2 kg 3.2 kg

[a]

Shipping dimensions

– Length 90 mm 90 mm 114 mm 114 mm

– Width 90 mm 90 mm 140 mm 140 mm

– Height 25 mm 25 mm 70 mm 70 mm

Keysight N4985A Operating and Service Manual 41

3 Specifications

Mechanical Dimensions

Figure 3-24 Mechanical dimensions of the N4985A-S30/N4985A-S50

[1]

amplifier

[1] Dimensions in millimeters.

42 Keysight N4985A Operating and Service Manual

Specifications 3

Figure 3-25 Mechanical dimensions of the N4985A-P15/N4985A-P25

amplifier

Keysight N4985A Operating and Service Manual 43

3 Specifications

THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK.

44 Keysight N4985A Operating and Service Manual

Keysight N4985A System Amplifiers
Operating and Service Manual

4 Operating Guide

Operating Instructions 46
Service and Maintenance 48

This chapter provides the operating instructions for the N4985A system amplifiers.

45

4 Operating Guide

Operating Instructions

Performance verification

The figures below show the setup used to verify the performance of the N4985A
system amplifiers.

A calibrated power splitter (or calibrated coupler) connected to the amplifier input
reference plane and to power sensor A, as shown, establishes the input power
level. The output power is measured on power sensor B. Measurements of gain
versus output power at frequencies of interest establish the amplifier
performance.

Figure 4-1 Verification setup with a power splitter

Figure 4-2 Verification setup with a calibrated coupler

46 Keysight N4985A Operating and Service Manual

Example Application

The N4985A amplifies the RF Source output power to the level needed to
characterize DUT performance.

The small size of the N4985A is easy to place close to the DUT input “Reference
Plane”. The high gain of the amplifier easily overcomes the cable losses from the
remote RF Source.

The figure below shows an amplified RF power measurement system using the
N4985A.

Operating Guide 4

Figure 4-3 Example of an amplified RF power measurement system

The DUT is characterized by setting the power level at the DUT input “Reference
Plane” and measuring the output power at various input power levels for each test

frequency.

The RF Source, used in this example, is a laboratory grade Synthesized Source or
Signal Generator with precise amplitude control (e.g. Keysight 83650L RF
Source). The power levels are measured using a power meter with two
measurement port sensors (A and B) (e.g. Keysight E4419B).

An RF power coupler provides a small, proportional amount of the amplified
power to power sensor A as shown in the above figure.

Keysight N4985A Operating and Service Manual 47

4 Operating Guide

Service and Maintenance

Service

The N4985A does not have internal adjustments and should not be opened; it
should only be repaired by service-trained personnel. Should it become necessary
to return the N4985A for repair or service, contact your nearest Keysight Sales
and Service Center.

Maintenance

The connectors of the N4985A, particularly the connector faces, must be kept
clean. Keysight recommends that the connectors be periodically inspected and
cleaned if necessary. For instructions on the connection and maintenance of your
connectors, refer to the Connector Care Quick Reference Card (08510- 90360).

48 Keysight N4985A Operating and Service Manual

This information is subject to change
without notice. Always refer to the
Keysight website for the latest
revision.

© Keysight Technologies 2013-2017
Edition 3, March 17, 2017

Printed in Malaysia

*N4985-90001*

N4985-90001

www.keysight.com