IEC 62604-2:2022

Surface acoustic wave (SAW) and bulk acoustic wave (BAW) duplexers of assessed quality - Part 2: Guidelines for the use

IEC 62604-2:2022 applies to duplexers which can separate receiving signals from transmitting signals and are key components for two-way radio communications, and which are generally used in mobile phone systems compliant with CDMA systems such as N-CDMA in second generation mobile telecommunication systems (2G), W-CDMA / UMTS (3G) or LTE (4G). These guidelines draw attention to some fundamental questions about the theory of SAW and BAW duplexers and how to use them, which will be considered by the user before he places an order for SAW and BAW duplexers for a new application. Such a procedure will be the user’s insurance against unsatisfactory performance. Because SAW and BAW duplexers have very similar performance for the usage, it is useful and convenient for users that both duplexers are described in one standard. This edition includes the following significant technical changes with respect to the previous edition:
- the term "cross-isolation" has been added to Clause 3;
- multiplexers are described.
NOTE In this document, SAW and BAW duplexers are treated simultaneously because both duplexers are used in the same manner, especially in mobile phone systems and have the same requirements of characteristics, test method and so on.

Duplexeurs à ondes acoustiques de surface (OAS) et à ondes acoustiques de volume (OAV) sous assurance de la qualité - Partie 2 : Lignes directrices d’utilisation

L’IEC 62604-2:2022 s’applique aux duplexeurs qui peuvent séparer les signaux en réception des signaux en émission et constituent des composants essentiels pour les radiocommunications bilatérales. Ils sont généralement utilisés dans les systèmes de téléphonie mobile conformes aux systèmes d’accès multiple par répartition en code (AMRC) comme les systèmes N-CDMA des systèmes de télécommunication mobile de seconde génération (2G), les systèmes W-CDMA/UMTS (3G) ou les systèmes LTE (4G). Les présentes lignes directrices attirent l’attention sur certaines des questions fondamentales concernant la théorie des duplexeurs à OAS et à OAV, et leurs modalités d’utilisation, qui sont à prendre en considération par l’utilisateur avant de commander un duplexeur à OAS ou à OAV pour une nouvelle application. Ainsi, l’utilisateur évite d’être confronté à des performances non satisfaisantes. Dans la mesure où les duplexeurs à OAS et à OAV présentent des performances très similaires dans leur utilisation, il est utile et pratique pour les utilisateurs que les deux types soient décrits dans une seule norme. Cette édition inclut les modifications techniques majeures suivantes par rapport à l’édition précédente:
- ajout du terme "isolation de polarisation croisée" à l’Article 3;
- description des multiplexeurs.

General Information

• Status: Published
• Publication Date: 31-Aug-2022
• ICS: 31.140 - Piezoelectric devices
• Technical Committee: TC 49 - Piezoelectric, dielectric and electrostatic devices and associated materials for frequency control, selection and detection
• Drafting Committee: WG 10 - TC 49/WG 10
• Current Stage: PPUB - Publication issued
• Start Date: 01-Sep-2022
• Completion Date: 05-Sep-2022

Relations

• Revises: IEC 62604-2:2017 - Surface acoustic wave (SAW) and bulk acoustic wave (BAW) duplexers of assessed quality - Part 2: Guidelines for the use
• Effective Date: 05-Sep-2023

Overview - IEC 62604-2:2022 (SAW & BAW duplexers guidelines)

IEC 62604-2:2022 provides practical guidelines for the use of surface acoustic wave (SAW) and bulk acoustic wave (BAW) duplexers of assessed quality. It covers duplexers that separate transmit (TX) and receive (RX) signals in two‑way radio communications and are commonly used in mobile phone systems (N‑CDMA/2G, W‑CDMA/UMTS/3G, LTE/4G). The standard helps users select and apply SAW and BAW duplexers by drawing attention to fundamental design and operational questions to consider before placing orders, reducing the risk of unsatisfactory performance.

Key technical topics and requirements

• Scope and purpose

  • Guidelines for selection, use and measurement of SAW and BAW duplexers in mobile systems.
  • Treats SAW and BAW duplexers together because they share use cases and characteristic requirements.

• Performance characteristics covered

  • Centre frequency, pass bandwidth, insertion loss (insertion attenuation), and isolation between TX and RX ports.
  • Typical TX and RX filter responses and isolation behavior over frequency.
  • Considerations for duplex gap (narrow gaps may favour TC‑SAW or BAW).

• Design and measurement topics

  • Basic function, structure and operation of duplexers, diplexers and multiplexers.
  • Cross‑isolation (new term added in this edition) and other terms/definitions.
  • Power durability, harmonics and inter‑modulation distortion, electrostatic protection, and measurement methods (e.g., four‑port network analyzer setups).
  • Practical elements such as phase shifters, balanced RX ports, and multiplexer configurations (multiplexers described in this edition).

• Standardization and ordering

  • Encourages selection from standardized performance specifications (centre frequency, bandwidth, attenuation, isolation) to simplify integration.

Practical applications and who uses this standard

IEC 62604-2:2022 is directly applicable to:

• RF engineers and antenna/system designers integrating duplexers into mobile handsets, modules, and base stations.
• Component engineers specifying SAW/BAW duplexers for LTE, UMTS, CDMA and related FDD systems.
• Procurement and quality teams evaluating supplier datasheets and test reports.
• Test laboratories and certification bodies performing duplexer characterization and compliance testing.

Use cases include minimizing TX–RX interference in mobile devices, choosing appropriate technology (SAW vs BAW) for narrow duplex gaps, and specifying test setups and durability criteria for production acceptance.

Related standards

• Other parts of the IEC 62604 series (surface acoustic wave and bulk acoustic wave duplexers of assessed quality) provide complementary specifications and test methods. Users should consult the full series and manufacturer detail specifications for complete technical requirements.

Standards Content (Sample)

IEC 62604-2 ®
Edition 3.0 2022-09
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Surface acoustic wave (SAW) and bulk acoustic wave (BAW) duplexers of
assessed quality –
Part 2: Guidelines for the use

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IEC 62604-2 ®
Edition 3.0 2022-09
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Surface acoustic wave (SAW) and bulk acoustic wave (BAW) duplexers of
assessed quality –
Part 2: Guidelines for the use
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.140 ISBN 978-2-8322-5653-4

– 2 – IEC 62604-2:2022 RLV © IEC 2022
CONTENTS
FOREWORD . 4
INTRODUCTION . 2
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
3.1 Response characteristics related terms . 8
3.2 SAW and BAW duplexers related terms . 8
4 Technical considerations . 8
5 Fundamentals of SAW and BAW duplexers. 9
5.1 Basic function . 9
5.1.1 General . 9
5.1.2 TX filter response (filter response from TX port to antenna port) . 10
5.1.3 RX filter response (filter response from antenna port to RX port) . 10
5.1.4 Isolation (isolation from TX port to RX port) . 10
5.2 Basic structure . 11
5.3 Principle of operation . 12
5.4 Diplexer . 17
5.5 Multiplexer . 18
6 SAW and BAW duplexer characteristics . 18
6.1 General conditions for SAW and BAW duplexers . 18
6.2 Typical characteristics of SAW and BAW duplexers . 21
6.2.1 UMTS duplexer . 21
6.2.2 US CDMA duplexer . 21
6.2.3 PCS CDMA duplexer . 22
6.2.4 LTE Band 1 + Band 3 multiplexer. 22
7 Application guidelines . 22
7.1 Power durability . 26
7.2 Harmonics and inter-modulation distortion . 27
7.3 Measurement method for the duplexer . 27
7.4 Electrostatic voltage protection . 29
Bibliography . 30

Figure 1 – Basic duplexer configuration . 9
Figure 2 – Basic TX filter response example of SAW and BAW duplexers . 11
Figure 3 – Basic RX filter response example of SAW and BAW duplexers . 11
Figure 4 – Basic isolation characteristics example of SAW and BAW duplexers . 11
Figure 5 – The block diagram of a duplexer . 13
Figure 6 – Demanded condition of TX part for duplexers . 15
Figure 7 – Phase rotation in TX part . 15
Figure 8 – Demanded condition of RX part for duplexers . 17
Figure 9 – Basic diplexer configuration . 17
Figure 10 – Basic multiplexer configuration . 18
Figure 11 – Typical wide range frequency response of TX filter . 19
Figure 12 – Typical wide range frequency response of RX filter for upper local system . 20

Figure 13 – Phase shifter by microstrip line on the surface of a ceramic package . 20
Figure 14 – Lumped element phase shifter . 21
Figure 15 – Duplexer configuration . 21
Figure 16 – Frequency characteristics of SAW duplexer for UMTS Band 1 system . 23
Figure 17 – Frequency characteristics of a SAW duplexer for US CDMA system . 25
Figure 18 – Frequency characteristics of BAW duplexer for PCS CDMA system . 26
Figure 19 – Frequency characteristics of SAW Band 1 + Band 3 multiplexer for LTE. 26
Figure 20 – Four-port-type network analyzer for duplexer measurement . 28
Figure 21 – Four-port-type network analyzer for measurement of a balanced RX port
duplexer. 29

Table 1 – Frequency allocation for typical LTE frequency division duplex (FDD) bands . 10

– 4 – IEC 62604-2:2022 RLV © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SURFACE ACOUSTIC WAVE (SAW) AND BULK
ACOUSTIC WAVE (BAW) DUPLEXERS
OF ASSESSED QUALITY –
Part 2: Guidelines for the use

FOREWORD
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
This redline version of the official IEC Standard allows the user to identify the changes made to
the previous edition IEC 62604-2:2017. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.

IEC 62604-2 has been prepared by IEC technical committee 49: Piezoelectric, dielectric and
electrostatic devices and associated materials for frequency control, selection and detection. It
is an International Standard.
This third edition cancels and replaces the second edition published in 2017. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the term "cross-isolation" has been added to Clause 3;
b) multiplexers are described.
NOTE In this document, SAW and BAW duplexers are treated simultaneously because both duplexers are used in
the same manner, especially in mobile phone systems and have the same requirements of characteristics, test
method and so on.
The text of this International Standard is based on the following documents:
Draft Report on voting
49/1361/CDV 49/1376/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
A list of all parts in the IEC 62604 series, published under the general title Surface acoustic
wave (SAW) and bulk acoustic wave (BAW) duplexers of assessed quality, can be found on the
IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC 62604-2:2022 RLV © IEC 2022
INTRODUCTION
While in 2G systems mainly dielectric duplexers have been used, the ongoing miniaturization
in 3G and 4G mobile communication systems promoted the development and application of
acoustic wave duplexers due to their small size, light weight and good electrical performance.
While standard surface acoustic wave (SAW) duplexers have been employed for applications
with moderate requirements regarding the steepness of individual filters, applications with
narrow duplex gap (e.g. Bands 2, 3, 8, 25), i.e., the frequency gap between receiving and
transmitting bands, require the application of temperature-compensated (TC) SAW or bulk
acoustic wave (BAW) technology, because of their better temperature characteristics and
resonator Q-factors.
Standard specifications, such as those of IEC, of which these guidelines form a part, and
national specifications or detail specifications issued by manufacturers will define the available
combinations of centre frequency, pass bandwidth and insertion attenuation for each sort of
transmitting and receiving filters and the isolation level between transmitter and receiver ports,
etc. These specifications are compiled to include a wide range of SAW and BAW duplexers with
standardized performances. It cannot be over-emphasized that the user should, wherever
possible, select his duplexers from these specifications, when available, even if it can lead to
making small modifications to his circuit to enable the use of standard duplexers. This applies
particularly to the selection of the nominal frequency band.

SURFACE ACOUSTIC WAVE (SAW) AND BULK
ACOUSTIC WAVE (BAW) DUPLEXERS
OF ASSESSED QUALITY –
Part 2: Guidelines for the use

1 Scope
This part of IEC 62604 concerns applies to duplexers which can separate receiving signals from
transmitting signals and are key components for two-way radio communications, and which are
generally used in mobile phone systems compliant with CDMA systems such as N-CDMA in
second generation mobile telecommunication systems (2G), W-CDMA / UMTS (3G) or LTE (4G).
While in 2G systems mainly dielectric duplexers have been used, the ongoing miniaturization
in 3G and 4G mobile communication systems promoted the development and application of
acoustic wave duplexers due to their small size, light weight and good electrical performance.
While standard surface acoustic wave (SAW) duplexers have been employed for applications
with moderate requirements regarding the steepness of individual filters, applications with
narrow duplex gap (e.g. Bands 2, 3, 8, 25), i.e. the frequency gap between receiving and
transmitting bands, require the application of temperature-compensated (TC) SAW or bulk
acoustic wave (BAW) technology, because of their better temperature characteristics and
resonator Q-factors.
It is neither the aim of these guidelines to explain theory, nor to attempt to cover all the
eventualities which may arise in practical circumstances. These guidelines draw attention to
some of the more fundamental questions about the theory of SAW and BAW duplexers and how
to use them, which should will be considered by the user before he places an order for SAW
and BAW duplexers for a new application. Such a procedure will be the user’s insurance against
unsatisfactory performance. Because SAW and BAW duplexers have very similar performance
for the usage, it is useful and convenient for users that both duplexers are described in one
standard.
Standard specifications, such as those of IEC, of which these guidelines form a part, and
national specifications or detail specifications issued by manufacturers will define the available
combinations of centre frequency, pass bandwidth and insertion attenuation for each sort of
transmitting and receiving filters and the isolation level between transmitter and receiver ports,
etc. These specifications are compiled to include a wide range of SAW and BAW duplexers with
standardized performances. It cannot be over-emphasized that the user should, wherever
possible, select his duplexers from these specifications, when available, even if it may lead to
making small modifications to his circuit to enable the use of standard duplexers. This applies
particularly to the selection of the nominal frequency band.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60862-1:2015, Surface acoustic wave (SAW) filters of assessed quality – Part 1: Generic
specification
IEC 62575-1:2015, Radio frequency (RF) bulk acoustic wave (BAW) filters of assessed quality
– Part 1: Generic specification

– 8 – IEC 62604-2:2022 RLV © IEC 2022
3 Terms and definitions
No terms and definitions are listed in this document.
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1 Response characteristics related terms
3.1.1
guard band
unused part of the radio spectrum between radio bands, for the purpose of preventing
interference
3.1.2
cross-isolation
leakage power ratio from one of the TX ports to one of the RX ports from another nominal
frequency band in a multiplexer
3.2 SAW and BAW duplexers related terms
3.2.1
phase shifter
device which changes the phase of signals, not the frequency of them
Note 1 to entry: This is a basic part of a duplexer.
3.2.2
void
vacancy in the IDT electrode caused by stress migration resulting from diffusing and/or transfer
of metal atoms forming part of the electrode
3.2.3
hillock
projection on the side or upper surface of the electrode caused by stress migration resulting
from diffusing and/or transfer of metal atoms forming part of the electrode
4 Technical considerations
It is of prime interest to a user that the duplexer characteristics should satisfy particular
specifications. The selection of the front-end circuits in user equipment and SAW and BAW
duplexers to meet such specifications should be a matter of agreement between the user and
the manufacturer.
Duplexer characteristics are usually expressed in terms of centre frequency, pass bandwidth and
insertion attenuation for each of transmitting and receiving filter parts in the duplexer and
isolation level between the transmitter and receiver ports. Since the SAW and BAW duplexer is
used in RF front-end of the user equipment, lower insertion attenuation, higher
isolation/rejection level, stronger power durability and smaller/thinner package dimensions are
strictly required.
5 Fundamentals of SAW and BAW duplexers
5.1 Basic function
5.1.1 General
Duplexers are necessary for frequency division duplex (FDD) equipment to receive and transmit
signals simultaneously. Duplexers are 3-port devices which consist of an antenna port, a
transmitter port (TX port) and a receiver port (RX port), as shown in Figure 1. The duplexer has
three basic functions:
• to transfer the transmitting signal from the TX port to the antenna port;
• to transfer the receiving signal from the antenna port to the RX port;
• to prevent transfer of the transmitting signal and noise from the TX port to the RX port.
The transmitting and the receiving frequencies are determined corresponding to each mobile
communication system. For example, Table 1 shows typical allocated frequency bands for
UMTS LTE.
Figure 1 – Basic duplexer configuration

– 10 – IEC 62604-2:2022 RLV © IEC 2022
Table 1 – Frequency allocation for typical
LTE frequency division duplex (FDD) bands
Downlink Downlink
Uplink frequency Band Uplink frequency
frequency frequency
Band
(MHz) (MHz) (MHz) (MHz)
1 1 920 – 1 980 2 110 – 2 170 16 2 010 – 2 025 2 585 – 2 600
2 1 850 – 1 910 1 930 – 1 990 17 704 – 716 734 – 746
3 1 710 – 1 785 1 805 – 1 880 18 815 – 830 860 – 875
4 1 710 – 1 755 2 110 – 2 155 19 830 – 845 875 – 890
5 824 – 849 869 – 894 20 832 – 862 791 – 821
6 830 – 840 875 – 885 21 1 447,9 – 1 462,9 1 495,5 – 1 510,9
7 2 500 – 2 570 2 620 – 2 690 22 3 410 – 3 490 3 510 – 3 590
8 880 – 915 925 – 960 23 2 000 – 2 020 2 180 – 2 200
9 1 749,9 – 1 784,9 1 844,9 – 1 879,9 24 1 626,5 – 1 660,5 1 525 – 1 559
10 1 710 – 1 770 2 110 – 2 170 25 1 850 – 1 915 1 930 – 1 995
11 1 427,9 – 1 447,9 1 475,9 – 1 495,9 26 814 – 849 859 – 894
12 699 – 716 729 – 746 27 807 – 824 852 – 869
13 777 – 787 746 – 756 28 703 – 748 758 – 803
14 788 – 798 758 – 768 30 2 305 – 2 315 2 350 – 2 360
15 1 900 – 1 920 2 600 – 2 620 31 452,5 – 457,5 462,5 – 467,5

NOTE For a user equipment, uplink frequency means transmitting frequency and downlink frequency means
receiving frequency respectively.
5.1.2 TX filter response (filter response from TX port to antenna port)
Figure 2 shows an example of frequency characteristics of the TX filter. The required frequency
characteristics are low insertion attenuation in the transmitting frequency band (f ), high
T
insertion attenuation in the receiving frequency band (f ) and good impedance matching.
R
5.1.3 RX filter response (filter response from antenna port to RX port)
Figure 3 shows an example of frequency characteristics of the RX filter. The required frequency
characteristics are low insertion attenuation in the receiving band (f ) and high insertion
R
).
attenuation in the transmitting frequency band (f
T
5.1.4 Isolation (isolation from TX port to RX port)
Figure 4 shows an example of isolation characteristics. One of the important functions for
duplexers is isolation characteristics, which show the frequency dependence of the leakage
power from the TX port to the RX port.

Figure 2 – Basic TX filter response example of SAW and BAW duplexers

Figure 3 – Basic RX filter response example of SAW and BAW duplexers

Figure 4 – Basic isolation characteristics example of SAW and BAW duplexers
5.2 Basic structure
Duplexers are 3-port devices/modules, which enable to transmit and receive signals
simultaneously through a common antenna. A basic structure of duplexers is shown in Figure 5.
SAW and BAW duplexers consist of a transmitter (TX) part and a receiver (RX) part. These two
parts, which may can add a phase shifter, are connected to an antenna port. The phase shifter
is utilized to prevent the interaction between the filters. In Figure 5, Z and Z correspond to the
t r
– 12 – IEC 62604-2:2022 RLV © IEC 2022
impedance of the TX and RX part at the antenna port side, whereas Z is the impedance of the
o
antenna port. The following conditions shall be fulfilled to achieve the duplexer functions.
Z ≅ Z and |Z | << |Z | in the TX pass band
o t o r
Z ≅ Z and |Z | << |Z | in the RX pass band
o r o t
Z ≅ Z and |Z | >> |Z | in the TX pass band
t o r o
Z ≅ Z and |Z | >> |Z | in the RX pass band
r o t o
DMS (double mode SAW) type filters which are also known as LCRF (longitudinally coupled
1) 2)
resonator filters) , ladder type SAW and BAW filters and other type of SAW filters such as
3)
interdigitated interdigital transducer (lIDT) resonator filters can be adopted as TX and RX
filters. High power durability is required in the TX filters.
5.3 Principle of operation
In the TX pass band, the impedance of the TX part in the antenna port side (Z ) is almost the
t
same as that of antenna (Z ), while that of the RX part (Z ) is much higher, which means that at
o r
the antenna port, the RX part has large reflection coefficient in this band.
Z ≅ Z and |Z | << |Z | in the TX pass band
o t o r
Z ≅ Z and |Z | >> |Z | in the TX pass band
t o r o
On the other hand, in the RX pass band, the impedance of the RX part at the antenna port side
(Z ) is almost the same as that of antenna (Z ), while that of the TX part (Z ) is much higher.
r o t
This also means the TX part has large reflection coefficient in this band.
Z ≅ Z and |Z | << |Z | in the RX pass band
o r o t
Z ≅ Z and |Z | >> |Z | in the RX pass band
r o t o
___________
1)
See IEC 60862-2:2012, 5.3.
2)
See IEC 60862-2:2012, 5.2.
3)
See IEC 60862-2:2012, 5.4.
Figure 5 – The block diagram of a duplexer
The transmitting signal applied to the TX port passes through the TX filter and then flows to the
antenna port, not the RX filter. The received signal from the antenna port does not flow to the
TX filter, but to the RX filter. As a result, the TX part and the RX part can share the common
antenna port. In the following explanation, the impedance of the antenna (Z ) is assumed to be
o
50 Ω. The S curve of the TX part at the antenna port side shall satisfy the demanded condition
indicated in Figure 6. The impedance of its pass band shall be around 50 Ω. In the rejection
band, the impedance shall be sufficiently larger than 50 Ω. In the actual duplexer, the S trace
in the Smith chart of the TX filter is rotated to its optimum state by a phase shifter, as shown in
Figure 7. On the other hand, the frequency characteristics of the amplitude of S remains the
same as that without phase shifter. Figure 8 shows the S frequency characteristics and S
21 11
demanded condition of the RX part.

– 14 – IEC 62604-2:2022 RLV © IEC 2022
–10
Mk1: 824 MHz
1,83 dB
1 2
Mk2: 849 MHz
1,85 dB
60 3
Pass band Rejection band
760 780 800 820 840 860 880 900 920 940 960
Frequency (MHz)
Pass band
The area demanded for pass band Z =
t
∼50 Ω (|Г |<0,33)
Rejection band
The area demanded for rejection band
Z >>50 Ω (|Г |∼1 0)
IEC
Attenuation (dB)
Figure 6 – Demanded condition of TX part for duplexers

Figure 7 – Phase rotation in TX part

– 16 – IEC 62604-2:2022 RLV © IEC 2022
Mk1: 824 MHz
3 4
85,10 dB
Mk2: 849 MHz
61,14 dB
760 780 800 820 840 860 880 900 920 940 960
Frequency (MHz)
Z
r
TX filter
Phase shifter
S
Pass band
The area demanded for pass band Z ≅
r
50 Ω (|Г |<0,33)
The area demanded for rejection band
Z >>50 Ω (|Г|≅ 1 0)
r
Rejection band
IEC
Attenuation (dB)
Figure 8 – Demanded condition of RX part for duplexers
5.4 Diplexer
Diplexers combine different frequency domains as shown in Figure 9. They have a structure
and an operation principle very similar to those of duplexers.

Figure 9 – Basic diplexer configuration

– 18 – IEC 62604-2:2022 RLV © IEC 2022
5.5 Multiplexer
Multiplexers combine a duplexer with other duplexers or filters which are used in respective
nominal frequency bands. As shown in Figure 10, every duplexer and filter is connected to the
common antenna port. In the case of Figure 10 b), a TDD (time division duplex) filter is added
to the two duplexers. They have a structure and an operation principle very similar to those of
duplexers.
a) Two duplexers combined
b) Two duplexers and one filter combined
Figure 10 – Basic multiplexer configuration
6 SAW and BAW duplexer characteristics
6.1 General conditions for SAW and BAW duplexers
The TX filter, RX filter and phase shifter, which compose SAW and BAW duplexers, as shown
in 5.2, are described in Clause 6. The duplexer assembly configuration is also explained here.
– TX filter
The TX filter of the duplexers needs high power durability against the transmitting signal.
To ensure the durability against high power, e.g., 1 W, a ladder filter or lattice filter is used

for the TX filter because of their higher power durability among several types of SAW and
BAW filters. SAW ladder and lattice filters are described in 5.2 of IEC 60862-2:2012 and
BAW ladder filters are described in 4.4 of IEC 62575-2:2012.
) and high insertion attenuation in the
Besides low insertion attenuation in the TX band (f
T
RX band (f ) described in 5.1, the high attenuation in the second harmonic (2f ) and the
R T
third harmonic (3f ) is also important. The attenuation in spurious frequency (f )
T SP
suppresses the inter-modulation signal at f = 2f – f . The typical frequency response is
R T SP
shown in Figure 11.
– RX filter
Transmitting power passes through the TX filter and attacks the antenna port side of the RX
filter. Filter types used for the TX filter can be adopted for the RX filter, but DMS (double
mode SAW) type filters which are also known as LCRF (longitudinally coupled resonator
filters) have the possibility of adoption with trap elements to block the transmitting power.
Besides low insertion attenuation in the RX band (f ) and high insertion attenuation in the
R
TX band (f ) described in 5.1, a heterodyne receiver with the intermediate frequency (f )
T IF
demands high attenuation in the local oscillation frequency (f ) and the image frequency
LO
(f = f + f for upper local system). The inter-modulation signal in f can be reduced by
IM LO IF R
high attenuation in the duplex image frequency (f = 2f – f ) frequency of e.g., 2f + f ,
DIM T R T R
2f – f , f + f and f – f . The typical frequency response is shown in Figure 12.
T R R T R T
– Phase shifter
There are various types of phase shifters according to duplexer configurations and the out-
of-band complex impedance of TX and RX filters. To construct the phase shifter of a delay
line with the desired electrical length, a stripline is located between the inside layers of a
package, or a microstrip line is located on the surface of a package as shown in Figure 13.
Figure 14 shows a lumped element phase shifter. A suitable number of lumped elements is
not fixed at three. In some cases no phase shifter is necessary.
– Duplexer configuration
Figure 15 shows two types of duplexer configurations. They have merits and demerits with
regard to characteristics, size, cost and other items.
Figure 15 a) shows a module type, which mounts SAW and BAW filters and other
components on a substrate, such as a printed board. Figure 15 b) shows a device type,
which seals the package after mounting SAW and BAW filter bare chips on a package, such
as multi-layered ceramics. In those two types, the TX and RX filters/chips are separated
from each other, and there is the possibility of a single filter/chip solution.

Figure 11 – Typical wide range frequency response of TX filter

– 20 – IEC 62604-2:2022 RLV © IEC 2022
f
R
f
DIM
f f
LO IM
f
T
Frequency
IEC
Figure 12 – Typical wide range frequency response of RX filter for upper local system

Figure 13 – Phase shifter by microstrip line on the surface of a ceramic package
Attenuation (dB)
Figure 14 – Lumped element phase shifter

a) Module type  b) Device type
Figure 15 – Duplexer configuration
6.2 Typical characteristics of SAW and BAW duplexers
6.2.1 UMTS duplexer
As an example of a duplexer for a UMTS system, a SAW duplexer for UMTS Band 1 is shown
in 6.2 Figure 16. The frequency regulation of Band 1 is provided by a third generation
partnership project (3GPP). The transmitter and receiver pass bands in the handset are
1 920 MHz to 1 980 MHz and 2 110 MHz to 2 170 MHz, respectively. Both frequency bands are
indicated by f and f in Figure 16. The size of this duplexer is typically
T R
4,9 mm × 4,9 mm × 1,7 mm. A 41° rotated Y cut X propagated LiNbO crystal is used as
substrate. The structure of the filter is a ladder (see 5.2 of IEC 60862-2:2012), and the electrode
material is made by Al-Ti alloy for high power durability.
Frequency characteristics of this SAW duplexer for UMTS Band 1 are shown in Figure 16. The
typical insertion attenuation from the TX port to the antenna port and that from the antenna port
to the RX port are 1,4 dB and 2,3 dB, respectively. The isolation values between transmitter
and receiver ports are typically 48 dB for the TX band and 40 dB for the RX band.
6.2.2 US CDMA duplexer
The frequency characteristics example of US CDMA duplexer is shown in Figure 17. This type
of duplexer is also applicable to UMTS Band 5. The TX passband frequency is 824 MHz to
849 MHz, while RX passband frequency is 869 MHz to 894 MHz. Both frequency bands are
indicated by f and f in the Figure 17. The dimension of this duplexer is typically
T R
3,8 mm × 3,8 mm × 1,6 mm. Y cut X propagated LiTaO with a rotation angle optimized around
36° is used as a substrate. The ladder type SAW filters are used for both TX and RX parts.
Typical insertion attenuation is 1,8 dB from TX port to antenna port. And 2,5 dB typical insertion
attenuation is from antenna port to RX port. The isolation between TX port and RX port is
typically 60 dB for the TX band and 47 dB for the RX band.

– 22 – IEC 62604-2:2022 RLV © IEC 2022
6.2.3 PCS CDMA duplexer
According to Table 1, the guard band or a gap distance between the transmitting and receiving
frequencies for UMTS band 2 or PCS band is relatively narrow, and high Q characteristics or a
sharp filter response in the transition band is required. From this requirement, BAW duplexers
which are composed of film bulk acoustic resonators (FBAR) or solidly mounted resonators
(SMR) are mainly used for PCS CDMA duplexers. The frequency characteristics example of a
PCS CDMA duplexer using FBAR is shown in Figure 18. The TX passband frequency is
1 850 MHz to 1 910 MHz, while the RX passband frequency is 1 930 MHz to 1 990 MHz. This
duplexer can comply with the specified maximum insertion attenuation of 3,5 dB for the TX band
and 4,0 dB for the RX band, with excellent transition band responses between the TX and RX
bands. Also, the specified minimum isolation values between the transmitter and receiver ports
are 54 dB for the TX band and 43 dB for the RX band.
6.2.4 LTE Band 1 + Band 3 multiplexer
The frequency characteristics example of Band 1 + Band 3 multiplexer using SAW is shown in
Figure 19. The frequency regulations of them are shown in Table 1. Cross-isolation is inherent
in multiplexer and one of the important functions for the multiplexer. At this example, the cross-
isolation values from the Band 1 TX port to the Band 3 Rx port are 59 dB both for the Band 1
TX band and the Band 3 RX band, and the other cross-isolation from the Band 3 TX port to the
Band 1 Rx port are 59 dB for the Band 3 TX band and 60 dB for the Band 1 RX band.

TX RX
f f
T R
1,6 1,7 1,8 1,9 2,0 2,1 2,2 2,3 2,4
Frequency (GHz)
IEC
a) Amplitude responses of the duplexer from TX port to antenna port and
from antenna port to RX port (near pass band)
Attenuation (dB)
f f
T R
1,6 1,7 1,8 1,9 2,0 2,1 2,2 2,3 2,4
Frequency (GHz)
IEC
b) Isolation characteristics of the duplexer between RX port and TX port
3f
T
2f
60 T
0 1,05 2,10 3,15 4,20 5,25 6,30
Frequency (GHz)
IEC
c) Amplitude response of the duplexer from TX port to antenna port (DC to 6 GHz)
Figure 16 – Frequency characteristics of SAW duplexer for UMTS Band 1 system

Attenuation (dB)
Attenuation (dB)
– 24 – IEC 62604-2:2022 RLV © IEC 2022

TX RX
f f
T R
760 780 800 820 840 860 880 900 920 940 960
Frequency (MHz) IEC
a) Amplitude responses of the duplexer from TX port to antenna port and
from antenna port to RX port (near pass band)
f f
T R
760 780 800 820 840 860 880 900 920 940 960
Frequency (MHz) IEC
b) Isolation characteristics of the duplexer between RX port and TX port
Attenuation (dB) Attenuation (dB)

–10
3f
T
2f
T
0 300 600 900 1 200 1 500 1 800 2 100 2 400 2 700 3 000
Frequency (MHz) IEC
c) Amplitude response of the duplexer from TX port to antenna port (DC to 3 GHz)
Figure 17 – Frequency characteristics of a SAW duplexer for US CDMA system
3,5 dB 4,0 dB
40 43 dB
52 dB
S
S
1 750 1 800 1 850 1 900 1 950 2 000 2 050
Frequency (MHz)
IEC
a) Amplitude responses of the duplexer from TX port to antenna port and
from antenna port to RX port (near pass band)
S
43 dB
54 dB
1 750 1 800 1 850 1 900 1 950 2 000 2 050
Frequency (MHz)
IEC
b) Isolation characteristics of the duplexer between RX port and TX port
Attenuation (dB)
Attenuation (dB) Attenuation (dB)

– 26 – IEC 62604-2:2022 RLV © IEC 2022
S
S
0 1 2 3 4 5 6
Frequency (GHz)
IEC
c) Amplitude responses of the duplexer from TX port to antenna port and
from antenna port to RX port (DC to 6 GHz)
© IEEE, 2006.
SOURCE: Reproduced from P.Bradley et al.: A 6-port Film Bulk Acoustic Resonator (FBAR) Multiplexer
For U.S. CDMA Handsets Permitting use of PCS, U.S. CDMA and GPS with a single Antenna, Proc. IEEE
Ultrasonics Symp., pp.325-328, 2006, with the permission of the IEEE.

Figure 18 – Frequency characteristics of BAW duplexer for PCS CDMA system

Figure 19 – Frequency characteristics of SAW Band 1 + Band 3 multiplexer for LTE
7 Application guidelines
7.1 Power durability
High power durability of about 1 W is necessary for SAW and BAW duplexers. There are two
modes of damage caused by power beyond the durability and the situation is severer for a SAW
duplexer than for a BAW duplexer.
The first mode is breakdown. High voltage momentarily destroys SAW electrodes. Input power
should be considered to prevent their breakdown.
Attenuation (dB)
The second mode is stress migration. The excessive repeated mechanical stress can induce
electrode deteriorations, such as voids and hillocks. They cause frequency shift and insertion
attenuation degradation of the SAW duplexer.
In order to protect the SAW duplexer from such deteriorations, and to keep the duplexer working
for a sufficient amount of time, the drive level shall be less than 1 W. Various technologies of
high power durability in SAW devices intended to extend their lifetime have been studied; these
are described in 5.5 of IEC 61019-2:2005.
In the case of a BAW duplexer, it is said that its durability is stronger than that of a SAW.
However, consideration of the drive level is necessary also for a BAW duplexer. More detailed
studies and reports are required technically.
7.2 Harmonics and inter-modulation distortion
Nonlinearity of SAW and BAW duplexers loaded in high power can cause harmonics, which
generates unwanted output signals in stop band areas, as shown by Figure 11 and Figure 12.
In addition inter-modulation distortion also occurs both in stop band and pass band areas.
Detailed technical information is described in 8.5.7 of IEC 60862-1:2015.
7.3 Measurement method for the duplexer
The measurement method shall basically be performed in accordance with the measurement
method of IEC 60862-1:2015 and IEC 62575-1:2015. However, in the evaluation of the duplexer,
the instructions given by the application notes from a vendor should be considered. Because
the duplexer is a three-port device, it is recommended to use multi-port-type network analyzers.
Figure 20 shows a schematic diagram of the measurement metho
...

IEC 62604-2 ®
Edition 3.0 2022-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Surface acoustic wave (SAW) and bulk acoustic wave (BAW) duplexers of
assessed quality –
Part 2: Guidelines for the use

Duplexeurs à ondes acoustiques de surface (OAS) et à ondes acoustiques de
volume (OAV) sous assurance de la qualité –
Partie 2: Lignes directrices d’utilisation

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IEC 62604-2 ®
Edition 3.0 2022-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Surface acoustic wave (SAW) and bulk acoustic wave (BAW) duplexers of

assessed quality –
Part 2: Guidelines for the use

Duplexeurs à ondes acoustiques de surface (OAS) et à ondes acoustiques de

volume (OAV) sous assurance de la qualité –

Partie 2: Lignes directrices d’utilisation

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.140 ISBN 978-2-8322-4875-1

– 2 – IEC 62604-2:2022 © IEC 2022
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
3.1 Response characteristics related terms . 7
3.2 SAW and BAW duplexers related terms . 8
4 Technical considerations . 8
5 Fundamentals of SAW and BAW duplexers. 8
5.1 Basic function . 8
5.1.1 General . 8
5.1.2 TX filter response (filter response from TX port to antenna port) . 9
5.1.3 RX filter response (filter response from antenna port to RX port) . 10
5.1.4 Isolation (isolation from TX port to RX port) . 10
5.2 Basic structure . 11
5.3 Principle of operation . 11
5.4 Diplexer . 14
5.5 Multiplexer . 15
6 SAW and BAW duplexer characteristics . 15
6.1 General conditions for SAW and BAW duplexers . 15
6.2 Typical characteristics of SAW and BAW duplexers . 18
6.2.1 UMTS duplexer . 18
6.2.2 US CDMA duplexer . 18
6.2.3 PCS CDMA duplexer . 18
6.2.4 LTE Band 1 + Band 3 multiplexer. 19
7 Application guidelines . 23
7.1 Power durability . 23
7.2 Harmonics and inter-modulation distortion . 23
7.3 Measurement method for the duplexer . 23
7.4 Electrostatic voltage protection . 25
Bibliography . 26

Figure 1 – Basic duplexer configuration . 9
Figure 2 – Basic TX filter response example of SAW and BAW duplexers . 10
Figure 3 – Basic RX filter response example of SAW and BAW duplexers . 10
Figure 4 – Basic isolation characteristics example of SAW and BAW duplexers . 11
Figure 5 – The block diagram of a duplexer . 12
Figure 6 – Demanded condition of TX part for duplexers . 13
Figure 7 – Phase rotation in TX part . 13
Figure 8 – Demanded condition of RX part for duplexers . 14
Figure 9 – Basic diplexer configuration . 14
Figure 10 – Basic multiplexer configuration . 15
Figure 11 – Typical wide range frequency response of TX filter . 16
Figure 12 – Typical wide range frequency response of RX filter for upper local system . 17

Figure 13 – Phase shifter by microstrip line on the surface of a ceramic package . 17
Figure 14 – Lumped element phase shifter . 17
Figure 15 – Duplexer configuration . 18
Figure 16 – Frequency characteristics of SAW duplexer for UMTS Band 1 system . 20
Figure 17 – Frequency characteristics of a SAW duplexer for US CDMA system . 21
Figure 18 – Frequency characteristics of BAW duplexer for PCS CDMA system . 22
Figure 19 – Frequency characteristics of SAW Band 1 + Band 3 multiplexer for LTE. 23
Figure 20 – Four-port-type network analyzer for duplexer measurement . 24
Figure 21 – Four-port-type network analyzer for measurement of a balanced RX port
duplexer. 25

Table 1 – Frequency allocation for typical LTE frequency division duplex (FDD) bands . 9

– 4 – IEC 62604-2:2022 © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SURFACE ACOUSTIC WAVE (SAW) AND BULK
ACOUSTIC WAVE (BAW) DUPLEXERS
OF ASSESSED QUALITY –
Part 2: Guidelines for the use

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 62604-2 has been prepared by IEC technical committee 49: Piezoelectric, dielectric and
electrostatic devices and associated materials for frequency control, selection and detection. It
is an International Standard.
This third edition cancels and replaces the second edition published in 2017. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the term "cross-isolation" has been added to Clause 3;
b) multiplexers are described.
NOTE In this document, SAW and BAW duplexers are treated simultaneously because both duplexers are used in
the same manner, especially in mobile phone systems and have the same requirements of characteristics, test
method and so on.
The text of this International Standard is based on the following documents:
Draft Report on voting
49/1361/CDV 49/1376/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
A list of all parts in the IEC 62604 series, published under the general title Surface acoustic
wave (SAW) and bulk acoustic wave (BAW) duplexers of assessed quality, can be found on the
IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC 62604-2:2022 © IEC 2022
INTRODUCTION
While in 2G systems mainly dielectric duplexers have been used, the ongoing miniaturization
in 3G and 4G mobile communication systems promoted the development and application of
acoustic wave duplexers due to their small size, light weight and good electrical performance.
While standard surface acoustic wave (SAW) duplexers have been employed for applications
with moderate requirements regarding the steepness of individual filters, applications with
narrow duplex gap (e.g. Bands 2, 3, 8, 25), i.e., the frequency gap between receiving and
transmitting bands, require the application of temperature-compensated (TC) SAW or bulk
acoustic wave (BAW) technology, because of their better temperature characteristics and
resonator Q-factors.
Standard specifications, such as those of IEC, of which these guidelines form a part, and
national specifications or detail specifications issued by manufacturers will define the available
combinations of centre frequency, pass bandwidth and insertion attenuation for each sort of
transmitting and receiving filters and the isolation level between transmitter and receiver ports,
etc. These specifications are compiled to include a wide range of SAW and BAW duplexers with
standardized performances. It cannot be over-emphasized that the user should, wherever
possible, select his duplexers from these specifications, when available, even if it can lead to
making small modifications to his circuit to enable the use of standard duplexers. This applies
particularly to the selection of the nominal frequency band.

SURFACE ACOUSTIC WAVE (SAW) AND BULK
ACOUSTIC WAVE (BAW) DUPLEXERS
OF ASSESSED QUALITY –
Part 2: Guidelines for the use

1 Scope
This part of IEC 62604 applies to duplexers which can separate receiving signals from
transmitting signals and are key components for two-way radio communications, and which are
generally used in mobile phone systems compliant with CDMA systems such as N-CDMA in
second generation mobile telecommunication systems (2G), W-CDMA / UMTS (3G) or LTE (4G).
These guidelines draw attention to some fundamental questions about the theory of SAW and
BAW duplexers and how to use them, which will be considered by the user before he places an
order for SAW and BAW duplexers for a new application. Such a procedure will be the user’s
insurance against unsatisfactory performance. Because SAW and BAW duplexers have very
similar performance for the usage, it is useful and convenient for users that both duplexers are
described in one standard.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60862-1, Surface acoustic wave (SAW) filters of assessed quality – Part 1: Generic
specification
IEC 62575-1, Radio frequency (RF) bulk acoustic wave (BAW) filters of assessed quality –
Part 1: Generic specification
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1 Response characteristics related terms
3.1.1
guard band
unused part of the radio spectrum between radio bands, for the purpose of preventing
interference
– 8 – IEC 62604-2:2022 © IEC 2022
3.1.2
cross-isolation
leakage power ratio from one of the TX ports to one of the RX ports from another nominal
frequency band in a multiplexer
3.2 SAW and BAW duplexers related terms
3.2.1
phase shifter
device which changes the phase of signals, not the frequency of them
Note 1 to entry: This is a basic part of a duplexer.
3.2.2
void
vacancy in the IDT electrode caused by stress migration resulting from diffusing and/or transfer
of metal atoms forming part of the electrode
3.2.3
hillock
projection on the side or upper surface of the electrode caused by stress migration resulting
from diffusing and/or transfer of metal atoms forming part of the electrode
4 Technical considerations
It is of prime interest to a user that the duplexer characteristics should satisfy particular
specifications. The selection of the front-end circuits in user equipment and SAW and BAW
duplexers to meet such specifications should be a matter of agreement between the user and
the manufacturer.
Duplexer characteristics are usually expressed in terms of centre frequency, pass bandwidth and
insertion attenuation for each of transmitting and receiving filter parts in the duplexer and
isolation level between the transmitter and receiver ports. Since the SAW and BAW duplexer is
used in RF front-end of the user equipment, lower insertion attenuation, higher
isolation/rejection level, stronger power durability and smaller/thinner package dimensions are
strictly required.
5 Fundamentals of SAW and BAW duplexers
5.1 Basic function
5.1.1 General
Duplexers are necessary for frequency division duplex (FDD) equipment to receive and transmit
signals simultaneously. Duplexers are 3-port devices which consist of an antenna port, a
transmitter port (TX port) and a receiver port (RX port), as shown in Figure 1. The duplexer has
three basic functions:
• to transfer the transmitting signal from the TX port to the antenna port;
• to transfer the receiving signal from the antenna port to the RX port;
• to prevent transfer of the transmitting signal and noise from the TX port to the RX port.
The transmitting and the receiving frequencies are determined corresponding to each mobile
communication system. For example, Table 1 shows typical allocated frequency bands for LTE.

Figure 1 – Basic duplexer configuration
Table 1 – Frequency allocation for typical
LTE frequency division duplex (FDD) bands
Downlink Downlink
Uplink frequency Band Uplink frequency
frequency frequency
Band
(MHz) (MHz) (MHz) (MHz)
1 1 920 – 1 980 2 110 – 2 170 16 2 010 – 2 025 2 585 – 2 600
2 1 850 – 1 910 1 930 – 1 990 17 704 – 716 734 – 746
3 1 710 – 1 785 1 805 – 1 880 18 815 – 830 860 – 875
4 1 710 – 1 755 2 110 – 2 155 19 830 – 845 875 – 890
5 824 – 849 869 – 894 20 832 – 862 791 – 821
6 830 – 840 875 – 885 21 1 447,9 – 1 462,9 1 495,5 – 1 510,9
7 2 500 – 2 570 2 620 – 2 690 22 3 410 – 3 490 3 510 – 3 590
8 880 – 915 925 – 960 23 2 000 – 2 020 2 180 – 2 200
9 1 749,9 – 1 784,9 1 844,9 – 1 879,9 24 1 626,5 – 1 660,5 1 525 – 1 559
10 1 710 – 1 770 2 110 – 2 170 25 1 850 – 1 915 1 930 – 1 995
11 1 427,9 – 1 447,9 1 475,9 – 1 495,9 26 814 – 849 859 – 894
12 699 – 716 729 – 746 27 807 – 824 852 – 869
13 777 – 787 746 – 756 28 703 – 748 758 – 803
14 788 – 798 758 – 768 30 2 305 – 2 315 2 350 – 2 360
15 1 900 – 1 920 2 600 – 2 620 31 452,5 – 457,5 462,5 – 467,5

NOTE For a user equipment, uplink frequency means transmitting frequency and downlink frequency means
receiving frequency respectively.
5.1.2 TX filter response (filter response from TX port to antenna port)
Figure 2 shows an example of frequency characteristics of the TX filter. The required frequency
characteristics are low insertion attenuation in the transmitting frequency band (f ), high
T
insertion attenuation in the receiving frequency band (f ) and good impedance matching.
R
– 10 – IEC 62604-2:2022 © IEC 2022
5.1.3 RX filter response (filter response from antenna port to RX port)
Figure 3 shows an example of frequency characteristics of the RX filter. The required frequency
characteristics are low insertion attenuation in the receiving band (f ) and high insertion
R
attenuation in the transmitting frequency band (f ).
T
5.1.4 Isolation (isolation from TX port to RX port)
Figure 4 shows an example of isolation characteristics. One of the important functions for
duplexers is isolation characteristics, which show the frequency dependence of the leakage
power from the TX port to the RX port.

Figure 2 – Basic TX filter response example of SAW and BAW duplexers

Figure 3 – Basic RX filter response example of SAW and BAW duplexers

Figure 4 – Basic isolation characteristics example of SAW and BAW duplexers
5.2 Basic structure
Duplexers are 3-port devices/modules, which enable to transmit and receive signals
simultaneously through a common antenna. A basic structure of duplexers is shown in Figure 5.
SAW and BAW duplexers consist of a transmitter (TX) part and a receiver (RX) part. These two
parts, which can add a phase shifter, are connected to an antenna port. The phase shifter is
utilized to prevent the interaction between the filters. In Figure 5, Z and Z correspond to the
t r
impedance of the TX and RX part at the antenna port side, whereas Z is the impedance of the
o
antenna port. The following conditions shall be fulfilled to achieve the duplexer functions.
Z ≅ Z and |Z | >> |Z | in the TX pass band
t o r o
Z ≅ Z and |Z | >> |Z | in the RX pass band
r o t o
DMS (double mode SAW) type filters which are also known as LCRF (longitudinally coupled
1) 2)
resonator filters) , ladder type SAW and BAW filters and other type of SAW filters such as
3)
interdigitated interdigital transducer (lIDT) resonator filters can be adopted as TX and RX
filters. High power durability is required in the TX filters.
5.3 Principle of operation
In the TX pass band, the impedance of the TX part in the antenna port side (Z ) is almost the
t
), while that of the RX part (Z ) is much higher, which means that at
same as that of antenna (Z
o r
the antenna port, the RX part has large reflection coefficient in this band.
Z ≅ Z and |Z | >> |Z | in the TX pass band
t o r o
On the other hand, in the RX pass band, the impedance of the RX part at the antenna port side
(Z ) is almost the same as that of antenna (Z ), while that of the TX part (Z ) is much higher.
r o t
This also means the TX part has large reflection coefficient in this band.
___________
1)
See IEC 60862-2:2012, 5.3.
2)
See IEC 60862-2:2012, 5.2.
3)
See IEC 60862-2:2012, 5.4.
– 12 – IEC 62604-2:2022 © IEC 2022
Z ≅ Z and |Z | >> |Z | in the RX pass band
r o t o
Figure 5 – The block diagram of a duplexer
The transmitting signal applied to the TX port passes through the TX filter and then flows to the
antenna port, not the RX filter. The received signal from the antenna port does not flow to the
TX filter, but to the RX filter. As a result, the TX part and the RX part can share the common
antenna port. In the following explanation, the impedance of the antenna (Z ) is assumed to be
o
50 Ω. The S curve of the TX part at the antenna port side shall satisfy the demanded condition
indicated in Figure 6. The impedance of its pass band shall be around 50 Ω. In the rejection
band, the impedance shall be sufficiently larger than 50 Ω. In the actual duplexer, the S trace
in the Smith chart of the TX filter is rotated to its optimum state by a phase shifter, as shown in
Figure 7. On the other hand, the frequency characteristics of the amplitude of S remains the
same as that without phase shifter. Figure 8 shows the S frequency characteristics and S
21 11
demanded condition of the RX part.

Figure 6 – Demanded condition of TX part for duplexers

Figure 7 – Phase rotation in TX part

– 14 – IEC 62604-2:2022 © IEC 2022

Figure 8 – Demanded condition of RX part for duplexers
5.4 Diplexer
Diplexers combine different frequency domains as shown in Figure 9. They have a structure
and an operation principle very similar to those of duplexers.

Figure 9 – Basic diplexer configuration

5.5 Multiplexer
Multiplexers combine a duplexer with other duplexers or filters which are used in respective
nominal frequency bands. As shown in Figure 10, every duplexer and filter is connected to the
common antenna port. In the case of Figure 10 b), a TDD (time division duplex) filter is added
to the two duplexers. They have a structure and an operation principle very similar to those of
duplexers.
a) Two duplexers combined
b) Two duplexers and one filter combined
Figure 10 – Basic multiplexer configuration
6 SAW and BAW duplexer characteristics
6.1 General conditions for SAW and BAW duplexers
The TX filter, RX filter and phase shifter, which compose SAW and BAW duplexers, as shown
in 5.2, are described in Clause 6. The duplexer assembly configuration is also explained here.
– TX filter
The TX filter of the duplexers needs high power durability against the transmitting signal.
To ensure the durability against high power, e.g., 1 W, a ladder filter or lattice filter is used

– 16 – IEC 62604-2:2022 © IEC 2022
for the TX filter because of their higher power durability among several types of SAW and
BAW filters. SAW ladder and lattice filters are described in 5.2 of IEC 60862-2:2012 and
BAW ladder filters are described in 4.4 of IEC 62575-2:2012.
) and high insertion attenuation in the
Besides low insertion attenuation in the TX band (f
T
RX band (f ) described in 5.1, the high attenuation in the second harmonic (2f ) and the
R T
third harmonic (3f ) is also important. The attenuation in spurious frequency (f )
T SP
suppresses the inter-modulation signal at f = 2f – f . The typical frequency response is
R T SP
shown in Figure 11.
– RX filter
Transmitting power passes through the TX filter and attacks the antenna port side of the RX
filter. Filter types used for the TX filter can be adopted for the RX filter, but DMS (double
mode SAW) type filters which are also known as LCRF (longitudinally coupled resonator
filters) have the possibility of adoption with trap elements to block the transmitting power.
Besides low insertion attenuation in the RX band (f ) and high insertion attenuation in the
R
TX band (f ) described in 5.1, a heterodyne receiver with the intermediate frequency (f )
T IF
demands high attenuation in the local oscillation frequency (f ) and the image frequency
LO
(f = f + f for upper local system). The inter-modulation signal in f can be reduced by
IM LO IF R
high attenuation in the frequency of e.g., 2f + f , 2f – f , f + f and f – f . The typical
T R T R R T R T
frequency response is shown in Figure 12.
– Phase shifter
There are various types of phase shifters according to duplexer configurations and the out-
of-band complex impedance of TX and RX filters. To construct the phase shifter of a delay
line with the desired electrical length, a stripline is located between the inside layers of a
package, or a microstrip line is located on the surface of a package as shown in Figure 13.
Figure 14 shows a lumped element phase shifter. A suitable number of lumped elements is
not fixed at three. In some cases no phase shifter is necessary.
– Duplexer configuration
Figure 15 shows two types of duplexer configurations. They have merits and demerits with
regard to characteristics, size, cost and other items.
Figure 15 a) shows a module type, which mounts SAW and BAW filters and other
components on a substrate, such as a printed board. Figure 15 b) shows a device type,
which seals the package after mounting SAW and BAW filter bare chips on a package, such
as multi-layered ceramics. In those two types, the TX and RX filters/chips are separated
from each other, and there is the possibility of a single filter/chip solution.

Figure 11 – Typical wide range frequency response of TX filter

Figure 12 – Typical wide range frequency response of RX filter for upper local system

Figure 13 – Phase shifter by microstrip line on the surface of a ceramic package

Figure 14 – Lumped element phase shifter

– 18 – IEC 62604-2:2022 © IEC 2022

a) Module type  b) Device type
Figure 15 – Duplexer configuration
6.2 Typical characteristics of SAW and BAW duplexers
6.2.1 UMTS duplexer
As an example of a duplexer for a UMTS system, a SAW duplexer for UMTS Band 1 is shown
in Figure 16. The frequency regulation of Band 1 is provided by a third generation partnership
project (3GPP). The transmitter and receiver pass bands in the handset are 1 920 MHz to
1 980 MHz and 2 110 MHz to 2 170 MHz, respectively. Both frequency bands are indicated by
f and f in Figure 16. The size of this duplexer is typically 4,9 mm × 4,9 mm × 1,7 mm. A 41°
T R
rotated Y cut X propagated LiNbO crystal is used as substrate. The structure of the filter is a
ladder (see 5.2 of IEC 60862-2:2012), and the electrode material is made by Al-Ti alloy for high
power durability.
Frequency characteristics of this SAW duplexer for UMTS Band 1 are shown in Figure 16. The
typical insertion attenuation from the TX port to the antenna port and that from the antenna port
to the RX port are 1,4 dB and 2,3 dB, respectively. The isolation values between transmitter
and receiver ports are typically 48 dB for the TX band and 40 dB for the RX band.
6.2.2 US CDMA duplexer
The frequency characteristics example of US CDMA duplexer is shown in Figure 17. This type
of duplexer is also applicable to UMTS Band 5. The TX passband frequency is 824 MHz to
849 MHz, while RX passband frequency is 869 MHz to 894 MHz. Both frequency bands are
indicated by f and f in the Figure 17. The dimension of this duplexer is typically
T R
3,8 mm × 3,8 mm × 1,6 mm. Y cut X propagated LiTaO with a rotation angle optimized around
36° is used as a substrate. The ladder type SAW filters are used for both TX and RX parts.
Typical insertion attenuation is 1,8 dB from TX port to antenna port. And 2,5 dB typical insertion
attenuation is from antenna port to RX port. The isolation between TX port and RX port is
typically 60 dB for the TX band and 47 dB for the RX band.
6.2.3 PCS CDMA duplexer
According to Table 1, the guard band or a gap distance between the transmitting and receiving
frequencies for UMTS band 2 or PCS band is relatively narrow, and high Q characteristics or a
sharp filter response in the transition band is required. From this requirement, BAW duplexers
which are composed of film bulk acoustic resonators (FBAR) or solidly mounted resonators
(SMR) are mainly used for PCS CDMA duplexers. The frequency characteristics example of a
PCS CDMA duplexer using FBAR is shown in Figure 18. The TX passband frequency is
1 850 MHz to 1 910 MHz, while the RX passband frequency is 1 930 MHz to 1 990 MHz. This
duplexer can comply with the specified maximum insertion attenuation of 3,5 dB for the TX band
and 4,0 dB for the RX band, with excellent transition band responses between the TX and RX
bands. Also, the specified minimum isolation values between the transmitter and receiver ports
are 54 dB for the TX band and 43 dB for the RX band.

6.2.4 LTE Band 1 + Band 3 multiplexer
The frequency characteristics example of Band 1 + Band 3 multiplexer using SAW is shown in
Figure 19. The frequency regulations of them are shown in Table 1. Cross-isolation is inherent
in multiplexer and one of the important functions for the multiplexer. At this example, the cross-
isolation values from the Band 1 TX port to the Band 3 Rx port are 59 dB both for the Band 1
TX band and the Band 3 RX band, and the other cross-isolation from the Band 3 TX port to the
Band 1 Rx port are 59 dB for the Band 3 TX band and 60 dB for the Band 1 RX band.

a) Amplitude responses of the duplexer from TX port to antenna port and
from antenna port to RX port (near pass band)

b) Isolation characteristics of the duplexer between RX port and TX port

– 20 – IEC 62604-2:2022 © IEC 2022

c) Amplitude response of the duplexer from TX port to antenna port (DC to 6 GHz)
Figure 16 – Frequency characteristics of SAW duplexer for UMTS Band 1 system

a) Amplitude responses of the duplexer from TX port to antenna port and
from antenna port to RX port (near pass band)

b) Isolation characteristics of the duplexer between RX port and TX port

c) Amplitude response of the duplexer from TX port to antenna port (DC to 3 GHz)
Figure 17 – Frequency characteristics of a SAW duplexer for US CDMA system

– 22 – IEC 62604-2:2022 © IEC 2022

a) Amplitude responses of the duplexer from TX port to antenna port and
from antenna port to RX port (near pass band)

b) Isolation characteristics of the duplexer between RX port and TX port

c) Amplitude responses of the duplexer from TX port to antenna port and
from antenna port to RX port (DC to 6 GHz)
© IEEE, 2006.
SOURCE: Reproduced from P.Bradley et al.: A 6-port Film Bulk Acoustic Resonator (FBAR) Multiplexer
For U.S. CDMA Handsets Permitting use of PCS, U.S. CDMA and GPS with a single Antenna, Proc. IEEE
Ultrasonics Symp., pp.325-328, 2006, with the permission of the IEEE.

Figure 18 – Frequency characteristics of BAW duplexer for PCS CDMA system

Figure 19 – Frequency characteristics of SAW Band 1 + Band 3 multiplexer for LTE
7 Application guidelines
7.1 Power durability
High power durability of about 1 W is necessary for SAW and BAW duplexers. There are two
modes of damage caused by power beyond the durability and the situation is severer for a SAW
duplexer than for a BAW duplexer.
The first mode is breakdown. High voltage momentarily destroys SAW electrodes. Input power
should be considered to prevent their breakdown.
The second mode is stress migration. The excessive repeated mechanical stress can induce
electrode deteriorations, such as voids and hillocks. They cause frequency shift and insertion
attenuation degradation of the SAW duplexer.
In order to protect the SAW duplexer from such deteriorations, and to keep the duplexer working
for a sufficient amount of time, the drive level shall be less than 1 W. Various technologies of
high power durability in SAW devices intended to extend their lifetime have been studied; these
are described in 5.5 of IEC 61019-2:2005.
In the case of a BAW duplexer, it is said that its durability is stronger than that of a SAW.
However, consideration of the drive level is necessary also for a BAW duplexer. More detailed
studies and reports are required technically.
7.2 Harmonics and inter-modulation distortion
Nonlinearity of SAW and BAW duplexers loaded in high power can cause harmonics, which
generates unwanted output signals in stop band areas, as shown by Figure 11 and Figure 12.
In addition inter-modulation distortion also occurs both in stop band and pass band areas.
Detailed technical information is described in 8.5.7 of IEC 60862-1:2015.
7.3 Measurement method for the duplexer
The measurement method shall basically be performed in accordance with the measurement
method of IEC 60862-1 and IEC 62575-1. However, in the evaluation of the duplexer, the
instructions given by the application notes from a vendor should be considered. Because the
duplexer is a three-port device, it is recommended to use multi-port-type network analyzers.

– 24 – IEC 62604-2:2022 © IEC 2022
Figure 20 shows a schematic diagram of the measurement method for a duplexer with a four-
port-type network analyzer, as an example.
However, a conventional two-port-type network analyzer can also be used for measuring the
characteristics between any two ports chosen from three ports of the duplexer with 50 Ω
termination of the unchosen port.
If the multiplexer has 5 ports or more, it can be measured in the same way as described above.
In other words, the unchosen ports should be connected to 50 Ω termination. It is also
convenient to use multi-port-type network analyzers that support more than 5 ports.

Figure 20 – Four-port-type network analyzer for duplexer measurement
4)
Adopting a balanced connection filter to the RX filter, a duplexer with a balanced RX port will
be realized. It can also be evaluated using four-port-type network analyzer as shown in
Figure 21.
___________
4)
See IEC 60862-2:2012, 5.3.5.
Figure 21 – Four-port-type network analyzer for measurement of
a balanced RX port duplexer
7.4 Electrostatic voltage protection
Since the duplexers are used in the front-end of the user equipment, electrostatic overstress
(discharge) can easily affect the device's antenna port, and a countermeasure against the static
electricity is generally required, particularly for SAW duplexers. As the electrode gap of IDT in
the SAW duplexer is very narrow, especially for the high frequency range, and it might be a
cause of degradation or destruction to apply static electricity to a SAW duplexer, it is necessary
to be careful not to apply static electricity or excessive voltage while transporting, assembling
and measuring.
If the piezoelectric material of duplexers has large pyro-electricity, excessive
...