Guidelines for the measurement method of nonlinearity for surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices in radio frequency (RF)

IEC 62761:2014-02(en-fr) gives the measurement method for nonlinear signals generated in the radio frequency (RF) surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices such as filters and duplexers, which are used in telecommunications, measuring equipment, radar systems and consumer products. It includes basic properties of non-linearity, and guidelines to setup the measurement system and to establish the measurement procedure of nonlinear signals generated in SAW/BAW devices.

Lignes directrices pour la méthode de mesure des non-linéarités pour les dispositifs à ondes acoustiques de surface (OAS) et à ondes acoustiques de volume (OAV) pour fréquences radioélectriques (RF)

IEC 62761:2014-02(en-fr) présente la méthode de mesure pour des signaux non-linéaires générés dans les dispositifs à ondes acoustiques de surface (OAS) et à ondes acoustiques de volume (OAV) pour les fréquences radioélectriques (RF), tels que les filtres et les duplexeurs utilisés dans les télécommunications, les équipements de mesure, les systèmes radar et les produits de grande consommation. Il inclut des propriétés de base de la non-linéarité, et des lignes directrices pour installer le système de mesure et pour établir la procédure de mesure des signaux non-linéaires générés dans des dispositifs à OAS/OAV.

General Information

Status
Published
Publication Date
18-Feb-2014
Current Stage
PPUB - Publication issued
Start Date
19-Feb-2014
Completion Date
19-Feb-2014
Ref Project

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IEC 62761
Edition 1.0 2014-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Guidelines for the measurement method of nonlinearity for surface acoustic
wave (SAW) and bulk acoustic wave (BAW) devices in radio frequency (RF)
Lignes directrices pour la méthode de mesure des non-linéarités pour les
dispositifs à ondes acoustiques de surface (OAS) et à ondes acoustiques de
volume (OAV) pour fréquences radioélectriques (RF)
IEC 62761:2014-02(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 62761
Edition 1.0 2014-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Guidelines for the measurement method of nonlinearity for surface acoustic
wave (SAW) and bulk acoustic wave (BAW) devices in radio frequency (RF)
Lignes directrices pour la méthode de mesure des non-linéarités pour les
dispositifs à ondes acoustiques de surface (OAS) et à ondes acoustiques de
volume (OAV) pour fréquences radioélectriques (RF)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX T
ICS 31.140 ISBN 978-2-8322-1425-1

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – 62761 © IEC:2014
CONTENTS

FOREWORD ........................................................................................................................... 3

INTRODUCTION ..................................................................................................................... 5

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms and definitions ...................................................................................................... 6

3.1 General terms .................................................................................................... 6

3.2 Response related terms ..................................................................................... 8

3.3 Nonlinearity related terms .................................................................................. 9

4 Basic properties of nonlinear system ............................................................................. 10

4.1 Behaviours of nonlinear system ....................................................................... 10

4.2 Measurement setup for nonlinearity ................................................................. 12

4.2.1 Harmonics measurement ................................................................ 12

4.2.2 IMD Measurement .......................................................................... 14

4.3 Influence of circuit impedance for nonlinearity measurement ............................ 16

4.4 Influence of circuit nonlinearity ......................................................................... 18

5 Nonlinearity measurement ............................................................................................. 18

5.1 Measurement equipment .................................................................................. 18

5.1.1 Signal generator and power amplifier .............................................. 18

5.1.2 Spectrum analyser .......................................................................... 18

5.1.3 Network analyser (optional) ............................................................ 19

5.1.4 Accessories .................................................................................... 19

5.2 Measurement Specifications ............................................................................ 19

5.3 Measurement procedure .................................................................................. 21

5.3.1 DUT check ...................................................................................... 21

5.3.2 Setup and check ............................................................................. 21

5.3.3 Data acquisition .............................................................................. 21

5.3.4 DUT final check .............................................................................. 22

5.4 Report.............................................................................................................. 22

Bibliography .......................................................................................................................... 23

Figure 1 – FBAR configuration ................................................................................................ 7

Figure 2 – SMR configuration.................................................................................................. 8

Figure 3 – Fundamental and harmonics output as a function of input signal power................ 12

Figure 4 – Basic setup for the harmonics measurement ........................................................ 13

Figure 5 – Practical setup for the harmonics measurement ................................................... 13

Figure 6 – Setup when the circulator/isolator is used ............................................................ 14

Figure 7 – Practical setup for the IMD measurement (two-tone test) ..................................... 15

Figure 8 – Practical setup for three-tone measurement ......................................................... 16

Figure 9 – Setup for IMD2 measurement of SAW/BAW antenna duplexers ............................ 16

Figure 10 – Range of deviation resulting from δ in dB ........................................................... 17

Figure 11 – Ideal IMD2 measurement setup for RF SAW/BAW duplexers .............................. 20

Figure 12 – Setup for the measurement of input signal intensity ........................................... 22

Table 1 – Frequencies f and f of input signals and target frequency f ............................... 20

a b t
---------------------- Page: 4 ----------------------
62761 © IEC:2014 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GUIDELINES FOR THE MEASUREMENT METHOD OF NONLINEARITY FOR
SURFACE ACOUSTIC WAVE (SAW) AND BULK ACOUSTIC WAVE (BAW)
DEVICES IN RADIO FREQUENCY (RF)
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

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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.

International Standard IEC 62761 has been prepared by IEC technical committee 49:

Piezoelectric, dielectric and electrostatic devices and associated materials for frequency

control, selection and detection.
The text of this standard is based on the following documents:
FDIS Report on voting
49/1091/FDIS 49/1098/RVD

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

---------------------- Page: 5 ----------------------
– 4 – 62761 © IEC:2014

The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication 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.
---------------------- Page: 6 ----------------------
62761 © IEC:2014 – 5 –
INTRODUCTION

Radio frequency (RF) surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices

such as filters and duplexers are now widely used in various communication systems. Due to

their small physical size, energy concentration causes generation of nonlinear signals even

when relatively small electric power is applied, and they may interfere with the
communications.

The features of these RF SAW/BAW devices are their small size, light weight, omission of

impedance and/or frequency tuning, high stability and high reliability. Nowadays, RF

SAW/BAW devices with low insertion attenuation are widely used in various applications in

the RF range.

In such applications, suppression of transmission and generation of unnecessary signals is

highly demanded. Since nonlinearity in the RF SAW/BAW devices will generate such signals,

its ultimate suppression is always crucial. In the same time, measurement method of

nonlinear signals should be well established from industrial points of view.

In passive filters like RF SAW/BAW ones, frequency selectivity is realized by impedance

matching/mismatching with peripheral circuitry. Thus impedance of peripheral circuitry shall

be set as specified for reliable and reproducible filter characterization. This is also true for

non-linear characteristics. It should be noted that even-order non-linearity, which is not

common in general passive electronic components, may occur in RF SAW/BAW devices

employing piezoelectric materials for electrical excitation and detection of SAWs/BAWs. This

is because crystallographic asymmetry is necessary for existence of piezoelectricity.

Therefore, measurement methods should be specifically established for non-linear behavior of

RF SAW/BAW devices.

This standard has been compiled in response to a generally expressed desire on the part of

both users and manufacturers for general Information on test condition guidance of RF

SAW/BAW filters, so that the filters may be used to their best advantage. To this end, general

and fundamental characteristics have been explained in this standard.
---------------------- Page: 7 ----------------------
– 6 – 62761 © IEC:2014
GUIDELINES FOR THE MEASUREMENT METHOD OF NONLINEARITY FOR
SURFACE ACOUSTIC WAVE (SAW) AND BULK ACOUSTIC WAVE (BAW)
DEVICES IN RADIO FREQUENCY (RF)
1 Scope

This International Standard gives the measurement method for nonlinear signals generated in

the radio frequency (RF) surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices

such as filters and duplexers, which are used in telecommunications, measuring equipment,

radar systems and consumer products.

The IEC 62761 includes basic properties of non-linearity, and guidelines to setup the

measurement system and to establish the measurement procedure of nonlinear signals

generated in SAW/BAW devices.

It is not the aim of this standard to explain theory, nor to attempt to cover all the eventualities

which may arise in practical circumstances. This standard draws attention to some of the

more fundamental questions, which the user has to consider before he/she places an order

for an RF SAW/BAW device for a new application. Such a procedure will be the user's

insurance against unsatisfactory performance.
2 Normative references
None
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 General terms
3.1.1
BAW duplexer
antenna duplexer composed of RF BAW resonators
3.1.2
BAW filter

filter characterised by a bulk acoustic wave which is usually generated by a pair of electrodes

and propagates along a thin film thickness direction
3.1.3
bulk acoustic wave
BAW

acoustic wave, propagating between the top and bottom surface of a piezoelectric structure

and traversing the entire thickness of the piezoelectric bulk

Note 1 to entry: The wave is excited by metal electrodes attached to both sides of the piezoelectric layer.

3.1.4
cut-off frequency

frequency of the pass-band at which the relative attenuation reaches a specified value

---------------------- Page: 8 ----------------------
62761 © IEC:2014 – 7 –
3.1.5
duplexer

device used in the frequency division duplex system, which enables the system to receive and

transmit signal through a common antenna simultaneously
3.1.6
film bulk acoustic resonator
FBAR

thin film BAW resonator consisting of a piezoelectric layer sandwiched between two electrode

layers with stress free top and bottom surface supported mechanically at the edge on a

substrate with cavity structure as shown in Figure 1 or membrane structure as an example

Note 1 to entry: This note applies to the French language only.
Upper electrode
Piezoelectric material
Supporting
layer
Lower electrode
Supporting
substrate
IEC 0652/14
Figure 1 – FBAR configuration
3.1.7
Receiver (Rx) band
frequency band used in a receiver part to detect signals from an antenna
3.1.8
Rx filter
filter used in a receiver part to eliminate unnecessary signals
Note 1 to entry: The Rx filter is a basic part of a duplexer.
3.1.9
SAW filter

filter characterised by one or more surface acoustic wave transmission line or resonant

elements, where the surface acoustic wave is usually generated by an interdigital transducer

and propagates along a substrate
3.1.10
solidly mounted resonator
SMR

BAW resonator, supporting the electrode/piezoelectric layer/electrode structure by a

sequence of additional thin films of alternately low and high acoustic impedance Z with

quarter wavelength layer, and these layers act as acoustic reflectors and decouple the

resonator acoustically from the substrate as shown in Figure 2 for example
Note 1 to entry: This note applies to the French language only.
---------------------- Page: 9 ----------------------
– 8 – 62761 © IEC:2014
Upper electrode
Piezoelectric material h
Lower electrode
Lower Z layer
Higher Z layer
Supporting
substrate
IEC 0653/14
Figure 2 – SMR configuration
3.1.11
surface acoustic wave
SAW

acoustic wave, propagating along a surface of an elastic substrate, whose amplitude decays

exponentially with substrate depth
[SOURCE: IEC 60862-1:2003, 2.2.1.1]
3.1.12
transmitter (Tx) band
frequency band used in a transmitter part to emit signals from an antenna
3.1.13
Tx filter

filter used in a transmitter part to eliminate unnecessary signals. It is a basic part of a

duplexer
3.2 Response related terms
3.2.1
insertion attenuation

logarithmic ratio of the power delivered directly to the load impedance before insertion of the

duplexer to the power delivered to the load impedance after insertion of the duplexer

3.2.2
pass band

band of frequencies in which the relative attenuation is equal to or less than a specified value

3.2.3
reflectivity

dimensionless measure of the degree of mismatch between two impedances Z and Z , i.e.,

1 2
Z − Z
1 2
, where Z and Z represent respectively the input and source impedance or the
1 2
Z + Z
1 2
output and load impedance

Note 1 to entry: The absolute value of reflectivity is called the reflection coefficient.

---------------------- Page: 10 ----------------------
62761 © IEC:2014 – 9 –
3.2.4
relative attenuation

difference between the attenuation at a given frequency and the attenuation at the reference

frequency
3.2.5
stop band

band of frequencies in which the relative attenuation is equal to or greater than a specified

value
3.2.6
transition band

band of frequencies between the cut-off frequency and the nearest point of the adjacent stop

band
3.3 Nonlinearity related terms
3.3.1
harmonics

non-linear distortion of a device response characterized by the appearance of frequencies at

the output equal to integral multiples of the original signal frequency
3.3.2
hysteresis
memory effect

phenomenon where the output is not determined only from the input and depends also on the

internal state, in other words, the history of the input
3.3.3
intercept point

power level where intensity of the non-linear signal generated by the intermodulation distortion (IMD) is equal to

that of two input signals at the output
Note 1 to entry: This note applies to the French language only.
3.3.4
intermodulation distortion
IMD

non-linear distortion of a device response characterized by the appearance of frequencies at the output equal to

the differences (or sums) of integral multiples of the two or more component frequencies present at the input

Note 1 to entry: This note applies to the French language only.
3.3.5
jammer signal
incoming unnecessary signal
3.3.6
nonlinear distortion

distortion of the signal waveform caused by nonlinearity of the system where the signal

transmits

Note 1 to entry: When the distortion is originated to the frequency dependence of the system signal transfer

function, it is called the linear distortion.
3.3.7
one decibel compression point

input power where gain, the ratio of the output to the input, decreases by 1 dB from the value

when the input is very weak
---------------------- Page: 11 ----------------------
– 10 – 62761 © IEC:2014
3.3.8
saturation

phenomenon where gain, the ratio of the output to the input, decreases and approaches to

zero when the input is large
3.3.9
three tone test

non-linearity measurement applying three sinusoidal signals with different frequencies

simultaneously
3.3.10
triple beat test
same as the three tone test
3.3.11
two tone test

non-linearity measurement applying two sinusoidal signals with different frequencies

simultaneously
4 Basic properties of nonlinear system
4.1 Behaviours of nonlinear system

Let us consider a response y(x) of a circuit or a device when a signal x is applied. When the

hysteresis (memory effect) is negligible or ignored, the Maclaurin expansion of y with respect

to x gives
1 1
2 3
(1)
y(x) = c x + c x + c x +
1 2 3
2 3

where c is the expansion coefficient. It should be noted that c = 0 for even m, when the

m m
circuit/device satisfies y(− x) = − y(x).
Here we consider a case when two sinusoidal signals with frequencies f and f and
a b

amplitudes a and a are simultaneously applied, namely, x = a cos(2πf t) + a cos(2πf t), and

a b a a b b
a is much greater than a . Then y is approximately given by
a b
2 2
   
c a c a
3 a 3 a
   
y ≈ c a 1+ cos(2πf t) + c a 1+ cos(2πf t)
1 a a 1 b b
   
4c 2c
 1   1 
2 2 3
c a c a c a
2 a 2 a 3 a
+ + cos(4πf t) + cos(6πf t)
a a
4 4 4
c a a c a a
2 a b 2 a b
(2)
+ cos{2π ( f + f )t}+ cos{2π ( f − f )t}
a b a b
2 2
2 2
c a a c a a
3 a b 3 a b
+ cos{2π (2 f + f )t}+ cos{2π (2 f − f )t}
a b a b
4 4
+

Equation (2) indicates how nonlinearity influences to the circuit/device output. Namely, the

first two terms indicate change in the transmission coefficients for a and a , and express

a b

saturation due to large signal input (usually c /c is negative). The three terms in the second

3 1

line express generation of harmonics with f = mf (m: integer). The two terms in the third line

express generation of new signals with f = f ± f called the second-order intermodulation

a b
---------------------- Page: 12 ----------------------
62761 © IEC:2014 – 11 –

distortion (IMD2). The remaining two terms in the fourth line express those with f = |2f ± f | or

a b
f = |2f ± f | called the third-order intermodulation distortion (IMD3).
b a

Here we consider a wireless receiver tuned for a signal with f = f . Incident signals with f = f /2

t t

and f = f /3 may be detected by the receiver after the harmonics generation, and may interfere

the main signal detection. Similarly, when two signals with f and f satisfying either

a b

f = |f ± f |, |2f ± f | or |f ± 2f | are incident to the receiver simultaneously, signals with f = f

t a b a b a b t

generated by IMD2 or IMD3 may also interfere the main signal detection. For transceivers

operating in the frequency division duplex (FDD) mode, transmitting signals with f=f may

cause IMD2 and/or IMD3 with an incident signal with f = f , and generated signals with f = f

b t

may also interfere the main signal detection. For transmitters, nonlinearity causes emission of

spurious signals, which may interfere with other wireless communications. These examples

clearly reveal importance to characterise nonlinear behaviour of RF systems and components

as well as the suppression.

For the characterisation of the transmission compression (saturation), we often use the input

signal level where the transmission coefficient decreases by 1 dB, which is called the 1dB

compression point (P ). On the other hand, so called the intercept point is used for the IMD

1dB

characterisation. That is, power P of the IMD2 signal with f = |f ± f | is expressed as

a±b a b

P = P P /OIP2 when signal levels are much lower than the saturation levels. In the

a±b oa ob

expression, P and P are the output power with f and f and OIP2 is called the output

oa ob a b
second-order intercept point. In decibels, the relation is rewritten as
...

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