Piezoelectric and dielectric devices for frequency control and selection - Glossary - Part 1: Piezoelectric and dielectric resonators

Gives the terms and definitions for piezoelectric and dielectric resonators representing the present state-of-the-art, which are intended for use in the standards and documents of IEC TC 49. This new edition takes into account new editions of IEC TC 49 publications.

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IEC/TS 61994-1
Edition 2.0 2007-08
Piezoelectric and dielectric devices for frequency control and selection –
Glossary –
Part 1: Piezoelectric and dielectric resonators
IEC/TS 61994-1:2007(E)
---------------------- Page: 1 ----------------------
Copyright © 2007 IEC, Geneva, Switzerland

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---------------------- Page: 2 ----------------------
IEC/TS 61994-1
Edition 2.0 2007-08
Piezoelectric and dielectric devices for frequency control and selection –
Glossary –
Part 1: Piezoelectric and dielectric resonators
ICS 31.140; 01.040.31 ISBN 2-8318-9298-8
---------------------- Page: 3 ----------------------
– 2 – TS 61994-1 © IEC:2007(E)


1 Scope...............................................................................................................................5

2 Normative references .......................................................................................................5

3 Terms and definitions .......................................................................................................5

Figure 1 – Configuration of a dielectric resonator (TE mode type) .....................................8


Figure 2 – Equivalent circuit of a piezoelectric vibrator (one-port resonator) ...........................9

Figure 3 – Frequency characteristics of the impedance near resonance................................11

Figure 4 – Equivalent circuit for a two-port SAW resonator ...................................................12

Figure 5 – Configuration of an interdigital transducer (IDT) ...................................................13

Figure 6 – Configuration of a one port SAW resonator ..........................................................16

Figure 7 – Configuration of a two port SAW resonator...........................................................21

---------------------- Page: 4 ----------------------
TS 61994-1 © IEC:2007(E) – 3 –
Part 1: Piezoelectric and dielectric resonators

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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

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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

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The main task of IEC technical committees is to prepare International Standards. In exceptional

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– the required support cannot be obtained for the publication of an International Standard,

despite repeated efforts, or

– the subject is still under technical development or where, for any other reason, there is the

future but no immediate possibility of an agreement on an International Standard.

IEC 61994-1, which is a technical specification, has been prepared by IEC technical committee

49: Piezoelectric and dielectric devices for frequency control and selection.

This second edition of IEC 61994-1 cancels and replaces the first edition published in 2003.

This edition constitutes a technical revision.
The main changes with respect to the previous edition are listed below:
– definitions updated;
– terminology given in orderly sequence;
---------------------- Page: 5 ----------------------
– 4 – TS 61994-1 © IEC:2007(E)
– drawings inserted for easier understanding.
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
49/761/DTS 49/766/RVC

Full information on the voting for the approval of this technical specification can be found in the

report on voting indicated in the above table.

This publication has been drafted in accordance with the IS0/lEC Directives, Part 2.

IEC 61994 consists of the following parts under the general title: Piezoelectric and dielectric

devices for frequency control and selection – Glossary:
- Part 1: Piezoelectric and dielectric resonators
- Part 2: Piezoelectric and dielectric filters
- Part 3: Piezoelectric oscillators
- Part 4-1: Piezoelectric materials – Synthetic quartz crystal
- Part 4-2: Piezoelectric and dielectric materials – Piezoelectric ceramics
- Part 4-3: Materials for dielectric devices
- Part 4-4: Materials – Materials for Surface Acoustic Wave (SAW) devices

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

maintenance result 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
• transformed into an international standard;
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
To be published.
---------------------- Page: 6 ----------------------
TS 61994-1 © IEC:2007(E) – 5 –
Part 1: Piezoelectric and dielectric resonators
1 Scope

This technical specification gives the terms and definitions for piezoelectric and dielectric

resonators representing the present state-of-the-art, which are intended for use in the standards

and documents of IEC technical committee 49.
2 Normative references

The following referenced documents are indispensable for the application 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 60050(561):1991, International Electrotechnical Vocabulary (IEV) – Chapter 561:

Piezoelectric devices for frequency control and selection
Amendment 1 (1995)

IEC 60122-1:2002, Quarts crystal units of assessed quality – Part-1: Generic specification

IEC 60642:1979, Piezoelectric ceramic resonators and resonator units for frequency control and

selection – Chapter I: Standard values and conditions – Chapter II: Measuring and test


IEC 61019-1:2004, Surface acoustic wave (SAW) resonators – Part 1: Generic specification

IEC 61338-1:2004, Waveguide type dielectric resonators – Part 1: Generic specification

3 Terms and definitions
adjustment tolerance

the maximum permissible deviation of the working frequency of a piezoelectric resonator from

the nominal frequency at the reference temperature under specified conditions
[IEV 561-02-16 modified]
ageing tolerance

the maximum permissible deviation of the working frequency of a piezoelectric resonator from its

initial frequency which is observed with the passage of time under specified conditions

[IEV 561-02-17 modified]
ageing – long-term parameter variation

relationship which exists between any parameter (for example resonance frequency) and time

[IEC 61019-1, 4.2.9]
apodisation (spurious suppression for SAW devices)

weighting method produced by the change in finger overlap over the length of the IDT to

suppress the transverse spurious modes
---------------------- Page: 7 ----------------------
– 6 – TS 61994-1 © IEC:2007(E)
[IEV 561-06-18 modified]
anti-resonance frequency

the higher of two frequencies of a piezoelectric resonator vibrating alone, under specified

conditions, at which the electrical impedance of the resonator is resistive
[IEV 561-02-10]
bus bar

common electrode region of an IDT which connects individual fingers together and also

connects the IDT to an external circuit (see Figure 5)
[IEV 561-06-15 modified]
capacitance ratio
r =

where C and C represent the shunt capacitance and the motional capacitance respectively

0 1
in the equivalent circuit (see Figure 2)
the capacitance ratio indicates one of the merits of the resonator
[IEC 61019-1, modified]
centre frequency of a two-port SAW resonator

arithmetic mean of two frequencies at which the attenuation relative to the minimum insertion

attenuation reaches a specified value
[IEC 61019-1,]
clamped capacitance (of a piezoelectric resonator)

the capacitance of a piezoelectric resonator measured at a frequency well above any

pronounced resonance

NOTE In practice, the value of the capacitance is often indirectly determined, because a direct measurement is

affected by the presence of factors such as lead inductance.
[IEV 561-02-35]
coaxial dielectric resonator

dielectric resonator characterized by a TEM mode field distribution with a coaxial waveguide

structure of finite length
[IEC 61338-1, 2.2.19]
---------------------- Page: 8 ----------------------
TS 61994-1 © IEC:2007(E) – 7 –
coplanar resonator

dielectric resonator characterised by a TEM mode field distribution. The structure is a

coplanar-line waveguide of finite length
[IEC 61338-1, 2.2.4]
coupling coefficient of SAW materials
the SAW electromechanical coupling coefficient is defined as follows:
k = 2

where Δv/v is the relative velocity change produced by short-circuiting the surface potential from

the open-circuit condition
[IEC 60862-2, 3.1.8; IEC 61019-1, 4.1.12]
crystal element

piezoelectric substrate cut to a given geometric shape, size and orientation with respect to the

crystallographic axes of the crystal
[IEC 60122-1, 2.2.1]
crystal resonator

the mounted crystal element that vibrates when an alternating electric field is applied between

the electrodes
[IEC 60122-1, 2.2.3 modified]
crystal unit
a crystal resonator mounted in an enclosure
[IEC 60122-1, 2.2.7]
d.c. breakdown voltage
the lowest d.c. voltage which causes the destruction of the resonator
[IEC 61019-1, 4.2.8]
dielectric material
material which predominantly exhibits dielectric properties
[IEC 61338-1, 2.2.1]
dielectric resonator
(ε ) and the structure of which is a
resonator using dielectrics with a high dielectric constant
dielectric waveguide of finite length as shown in Figure 1
[IEC 61338-1, 2.2.10]
---------------------- Page: 9 ----------------------
– 8 – TS 61994-1 © IEC:2007(E)
X ε X
IEC 1697/07
Figure 1 – Configuration of a dielectric resonator (TE mode type)
dielectric support

element supporting a dielectric resonator. The support is generally used for TE mode

resonators and has a low dielectric constant (see Figure 1)
[IEC 61338-1, 2.2.11]
drive level dependency

the permissible deviation of resonance frequency due to variation of the level of drive. The effect

of changes in drive level conditions upon the resonance resistance of the crystal unit

[IEC 60122-1, 2.2.37 modified]
electrode (of piezoelectric resonator)

an electrically conductive plate in proximity to or film in contact with a face of a crystal or ceramic

element by means of which a polarizing or driving field is applied to the element

[IEC 60122-1, 2.2.2 modified]
electromechanical coupling factor (of piezoelectric resonator)

a certain combination of elastic, dielectric and piezoelectric constants which appears naturally in

the expression of impedance of a resonator. A different factor arises in each particular family of

mode of vibration. The factor is closely related to the relative frequency spacing and is a

convenient measure of piezoelectric transduction.

Alternatively, the coupling factor may be interpreted as the square root of the ratio of the

electrical or mechanical work which can be accomplished to the total energy stored from a

mechanical or electrical power source for a particular set of boundary conditions

[IEC 60642, 3.2.14 modified]

an enclosure of specific outline dimensions and material with a defined method of sealing

protecting the resonator and providing means of electrical connections to the circuit

---------------------- Page: 10 ----------------------
TS 61994-1 © IEC:2007(E) – 9 –
[IEV 561-01-12 modified, IEC 60122-1, 2.2.5 modified, IEC 60642, 3.1.5 modified]
equivalent circuit (of piezoelectric resonators)

the electrical circuit which has the same characteristics as a piezoelectric resonator in the

immediate neighbourhood of resonance

NOTE For example, one port piezoelectric resonator consists of series element L , C , R in parallel with C , as

1 1 1 0

shown in Figure 2 where L1, C1, R1 represent the motional inductance, capacitance and resistance respectively and C0

the shunt capacitance. The circuit of Figure 2 has the same impedance as a piezoelectric resonator in the

neighbourhood of resonance.
[IEV 561-02-07 modified]
1 C 1
IEC 1698/07
L motional inductance C shunt capacitance (static capacitance)
1 0
C motional capacitance Z = R + jX impedance of the circuit
1 e e
R motional resistance
Figure 2 – Equivalent circuit of a piezoelectric vibrator (one-port resonator)
external quality factor

quality factor due to the energy loss in the external circuit, excluding the energy dissipated in the

[IEC 61338-1, 2.2.27]
figure of merit
M =Q /r
Q is the quality factor,
r is the capacitance ratio.
the value indicates the activity of the resonator
[IEC 60122-1, IEC 61019-1, modified]

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