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IEC 60444-6
Edition 3.0 2021-09
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Measurement of quartz crystal unit parameters –
Part 6: Measurement of drive level dependence (DLD)
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IEC 60444-6
Edition 3.0 2021-09
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Measurement of quartz crystal unit parameters –
Part 6: Measurement of drive level dependence (DLD)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.140 ISBN 978-2-8322-4188-2
– 2 – IEC 60444-6:2021 RLV © IEC 2021
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references. 6
3 Terms and definitions . 6
4 DLD effects . 6
4.1 Reversible changes in frequency and resistance . 6
4.2 Irreversible changes in frequency and resistance . 7
4.3 Causes of DLD effects . 7
5 Drive levels for DLD measurement . 7
6 Test methods . 8
6.1 Method A (fast standard measurement method) . 8
6.1.1 Testing at two drive levels . 8
6.1.2 Testing according to specification . 9
6.2 Method B (Multi-level reference measurement method) . 10
Annexe A (normative) Relationship between electrical drive level and mechanical
displacement of quartz crystal units . 13
Annex B (normative) Method C: DLD measurement with oscillation circuit . 17
Bibliography . 22
γ
Figure 1 – Maximum tolerable resistance ratio for the drive level dependence as a
function of the resistances R or R . 10
12 13
Figure B.1 – Insertion of a quartz crystal unit in an oscillator . 17
Figure B.2 – Crystal unit loss resistance as a function of dissipated power . 18
Figure B.3 – Behaviour of the R of a quartz crystal unit . 19
r
Figure B.4 – Block diagram of circuit system . 19
Figure B.5 – Installed −R in scanned drive level range . 20
osc
Figure B.6 – Drive level behaviour of a quartz crystal unit if −R = 70 Ω is used as
osc
test limit in the Annex B test . 20
Figure B.7 – Principal schematic diagram of the go/no-go test circuit . 21
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEASUREMENT OF QUARTZ CRYSTAL UNIT PARAMETERS –
Part 6: Measurement of drive level dependence (DLD)
FOREWORD
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This redline version of the official IEC Standard allows the user to identify the changes made to
the previous edition IEC 60444-6:2013. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.
– 4 – IEC 60444-6:2021 RLV © IEC 2021
IEC 60444-6 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 2013. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) some equations have been removed and corrected;
b) it has been specified in the note of the Scope that the measurement methods specified in
this document are not only applicable to AT-cut but also to other crystal cuts and vibration
modes.
The text of this International Standard is based on the following documents:
FDIS Report on voting
49/1374/FDIS 49/1377/RVD
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 /members_experts/refdocs. The main document types developed by IEC are
described in greater detail at /standardsdev/publications.
A list of all parts in the IEC 60444 series, published under the general title Measurement of
quartz crystal unit parameters, 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 "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.
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.
INTRODUCTION
The drive level (expressed as power/voltage across or current through the crystal unit) forces
the resonator to produce mechanical oscillations by way of piezoelectric effect. In this process,
the acceleration work is converted to kinetic and elastic energy and the power loss to heat. The
latter conversion is due to the inner and outer friction of the quartz resonator.
The frictional losses depend on the velocity of the vibrating masses and increase when the
oscillation is no longer linear or when critical velocities, elongations or strains, excursions or
accelerations are attained in the quartz resonator or at its surfaces and mounting points (see
Annex A). This causes changes in resistance and frequency, as well as further changes due to
the temperature dependence of these parameters.
At “high” drive levels (e.g. above 1 mW or 1 mA for AT-cut crystal units) changes are observed
by all crystal units and these also can result in irreversible amplitude and frequency changes.
Any further increase of the drive level may could destroy the resonator.
Apart from this effect, changes in frequency and resistance are observed at “low” drive levels
in some crystal units (e.g. below 1 mW μW or 50 μA for AT-cut crystal units). In this case, if the
loop gain is not sufficient, the start-up of the oscillation is difficult. In crystal filters, the
transducer attenuation and ripple will change.
Furthermore, the coupling between a specified mode of vibration and other modes (e.g. of the
resonator itself, the mounting and the back-fill gas) also depends on the level of drive.
Due to the differing temperature response of these modes, these couplings give rise to changes
of frequency and resistance of the specified mode within narrow temperature ranges. These
changes increase with increasing drive level. However, this effect will not be considered further
in this part of IEC 60444.
The first edition of IEC 60444-6 was published in 1995. However, it has not been revised until
today. In the meantime the demand for tighter specification and measurement of DLD has
increased.
In this new edition, the concept of DLD in IEC 60444-6:19952013 is maintained. However, the
more suitable contents for the user’s severe requirements have been introduced. Al
...