IEC TS 61994-3:2021

IEC TS 61994-3 ®
Edition 3.0 2021-01
TECHNICAL
SPECIFICATION
Piezoelectric, dielectric and electrostatic devices and associated materials for
frequency control, selection and detection – Glossary –
Part 3: Piezoelectric, dielectric and electrostatic oscillators
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IEC TS 61994-3 ®
Edition 3.0 2021-01
TECHNICAL
SPECIFICATION
Piezoelectric, dielectric and electrostatic devices and associated materials for

frequency control, selection and detection – Glossary –

Part 3: Piezoelectric, dielectric and electrostatic oscillators

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.140; 01.040.31 ISBN 978-2-8322-9306-5

– 2 – IEC TS 61994-3:2021 © IEC 2021
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
Bibliography . 19

Figure 1 – Characteristics of an output waveform . 7
Figure 2 – Example of the use of frequency offset. 8
Figure 3 – Linearity of frequency modulation deviation . 10
Figure 4 – Basic configuration of one-port SAW resonator with open-circuited metal strip
arrays . 11
Figure 5 – Clock signal with period jitter. 12
Figure 6 – Definition of start-up time . 16
Figure 7 – Basic configurations of two-port SAW resonators with short-circuited metal
strip arrays . 18

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PIEZOELECTRIC, DIELECTRIC AND ELECTROSTATIC DEVICES
AND ASSOCIATED MATERIALS FOR FREQUENCY CONTROL,
SELECTION AND DETECTION – GLOSSARY –

Part 3: Piezoelectric, dielectric and electrostatic oscillators

FOREWORD
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Technical specifications are subject to review within three years of publication to decide whether
they can be transformed into International Standards.
IEC TS 61994-3, which is a technical specification, has been prepared by IEC technical
committee 49: Piezoelectric, dielectric and electrostatic devices and associated materials for
frequency control, selection and detection.

– 4 – IEC TS 61994-3:2021 © IEC 2021
This third edition of IEC 61994-3 cancels and replaces the second edition published in 2011.
This edition constitutes a technical revision.
The main changes with respect to the previous edition are as listed below:
– some definitions have been updated;
– the terminology given in IEC 60679-1:2017 has been taken into account;
– new terminologies are added.
The text of this Technical Specification is based on the following documents:
Enquiry draft Report on voting
49/1348/DTS 49/1355/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 document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61994 series, published under the general title Piezoelectric,
dielectric and electrostatic devices and associated materials for frequency control, selection and
detection – Glossary, can be found on the IEC website.
Future standards in this series will carry the new general title as cited above. Titles of existing
standards in this series will be updated at the time of the next edition.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://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.
PIEZOELECTRIC, DIELECTRIC AND ELECTROSTATIC DEVICES
AND ASSOCIATED MATERIALS FOR FREQUENCY CONTROL,
SELECTION AND DETECTION – GLOSSARY –

Part 3: Piezoelectric, dielectric and electrostatic oscillators

1 Scope
This part of IEC 61994 gives the terms and definitions for piezoelectric, dielectric and
electrostatic oscillators representing the state of the art, which are intended for use in the
standards and documents of IEC TC 49.
2 Normative references
There are no normative references in this document.
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 http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
adjustment frequency
frequency to which an oscillator must be adjusted, under a particular combination of operating
conditions, in order to meet the requirement for the frequency tolerance specification over the
specified range of operating conditions
Note 1 to entry: Adjustment frequency corresponds to nominal frequency plus frequency offset.
[SOURCE: IEC 60679-1:2017, 3.2.22]
3.2
ADEV of fractional frequency fluctuation
Allan deviation of fractional frequency fluctuation
measure in the time domain of the short-term frequency stability of oscillator, based on the
statistical properties of a number of frequency measurements, each representing an average of
the frequency over the specified sampling interval τ
Note 1 to entry: The preferred measure of fractional frequency fluctuation is:
M −1 2
 
σ (τ ) ≅ (YY− )
 
y kk+1
∑
21(M − )
 
 k =1 
where
Y are the average fractional frequency fluctuations obtained sequentially, with no systematic
k
dead time between measurements;
τ is the sample time over which measurements are averaged;

– 6 – IEC TS 61994-3:2021 © IEC 2021
M is the number of measurements.
Note 2 to entry: The confidence of the estimate improves as M increases.
[SOURCE: IEC 60679-1:2017, 3.2.38, modified – ADEV of fractional frequency fluctuation has
been replaced as the first preferred term. The meaning of the symbols used in the
mathematical formula has been added, as well as Note 2 to entry.]
3.3
AVAR of fractional frequency fluctuation
Allan variance of fractional frequency fluctuation
unbiased estimate of the preferred definition in the time domain of the short-term stability
characteristic of the oscillator output frequency
Note 1 to entry: The preferred measure of fractional frequency fluctuation is:
M −1
2 2
σ (τ ) ≅ (Y −Y )
y k +1 k
∑
(M )
2 −1
k =1
where
Y are the average fractional frequency fluctuations obtained sequentially, with no systematic
k
dead time between measurements;
τ is the sample time over which measurements are averaged;
M is the number of measurements.
Note 2 to entry: The confidence of the estimate improves as M increases.
[SOURCE: IEC 60679-1:2017, 3.2.37, modified – The term "Allan variance AVAR of fractional
frequency fluctuation" has been deleted. And AVAR of fractional frequency fluctuation has been
replaced as the preferred term.]
3.4
amplitude modulation distortion
non-linear distortion in which the relative magnitudes of the spectral components of the
modulating signal waveform are modified
Note 1 to entry: The test procedure is provided in 4.5.22.3 of IEC
...