SIST EN IEC 60444-11:2026

• Abstract:

  IEC 60444-11:2026 defines the standard method of measuring load resonance frequency fL at the nominal value of CL, and the determination of the effective load capacitance CLeff at the nominal frequency for crystals with the figure of merit M > 4.; This edition includes the following significant technical changes with respect to the previous edition:; a) key content of withdrawn IEC TR 60444-4 is reproduced as Annex A;; b) some formulae in the first edition have been corrected.

• Status: Published
• Public Enquiry End Date: 31-May-2025
• Publication Date: 17-Jun-2026
• ICS: 31.140 - Piezoelectric devices
• Technical Committee: I11 - Imaginarni 11
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 09-Jun-2026
• Due Date: 14-Aug-2026
• Completion Date: 18-Jun-2026
• Ref Project: EN IEC 60444-11:2026 - Measurement of quartz crystal unit parameters - Part 11: Standard method for the determination of the load resonance frequency fL and the effective load capacitance CLeff using automatic network analyzer techniques and error correction

• Replaces: SIST EN 60444-11:2011 - Measurement of quartz crystal unit parameters - Part 11: Standard method for the determination of the load resonance frequency fL and the effective load capacitance CLeff using automatic network analyzer techniques and error correction (IEC 60444-11:2010)
• Effective Date: 01-Jul-2026
• Refers: SIST EN 60122-1:2004/A1:2018 - Quartz crystal units of assessed quality - Part 1: Generic specification
• Effective Date: 19-May-2026
• Refers: SIST EN 60444-1:2002 - Measurement of quartz crystal unit parameters by zero phase technique in a pi-network -- Part 1: Basic method for the measurement of resonance frequency and resonance resistance of quartz crystal units by zero phase technique in a pi-network
• Effective Date: 19-May-2026
• Refers: SIST EN 60444-1:2002/A1:2002 - Measurement of quartz crystal unit parameters by zero phase technique in a pi-network -- Part 1: Basic method for the measurement of resonance frequency and resonance resistance of quartz crystal units by zero phase technique in a pi-network
• Effective Date: 19-May-2026
• Refers: SIST EN 60122-1:2004 - Quartz crystal units of assessed quality -- Part 1: Generic specification
• Effective Date: 19-May-2026

SIST EN IEC 60444-11:2026 is the Slovenian adoption of EN IEC 60444-11:2026, which adopts IEC 60444-11:2026. It specifies a standard automatic network analyzer method for measuring the load resonance frequency fL at nominal CL and for determining the effective load capacitance CLeff at the nominal frequency for quartz crystal units with figure of merit M > 4. The document is intended for people who test, qualify, or compare quartz crystal units in frequency-control work.

What does SIST EN IEC 60444-11:2026 specify?

SIST EN IEC 60444-11:2026 covers a measurement method for quartz crystal unit parameters using automatic network analyzer techniques with error correction. It is focused on practical determination of fL and CLeff, not on a full crystal characterization method.

The document is organized into five main clauses and one informative annex:

Part	What it covers
Clause 1	Scope
Clause 2	Normative references
Clause 3	Terms and definitions
Clause 4	General concepts, including the load resonance frequencies and effective load capacitance
Clause 5	Reference plane, test conditions, measurement principle, and error evaluation
Annex A (informative)	Manual measuring method using physical load capacitance, kept for user convenience

Annex A is informative and describes the older manual approach. In case of dispute, the automatic network analyzer method in the main body is the reference method.

What are the key requirements of SIST EN IEC 60444-11:2026?

The method is defined for crystals with M > 4

Clause 1 limits the method to quartz crystal units with figure of merit M greater than 4. In practice, this tells the reader whether the crystal is in the intended measurement range before setting up the test.

The document uses the lower of two load-resonant frequencies

Clause 4 explains that a crystal with a load capacitance has two intersection frequencies where the combination becomes resistive. The standard load resonance frequency fL is the lower of these two. This matters because the measurement must target the correct resonance point, not just any frequency where the reactance balance is reached.

CLeff is derived from reactance at the nominal frequency

Clause 4 also defines effective load capacitance CLeff from the crystal reactance at the nominal frequency. In practice, the reader measures the reactance at the specified nominal frequency and calculates CLeff from that value.

The reference plane and test conditions are controlled

Clause 5.1 states the reference plane as in IEC 60444-5 and requires that the crystal case is not grounded. It also states that the generator output level is set so the crystal is measured at its nominal drive level at series resonance. This matters because drive level affects the measured result and must be comparable from one test setup to another.

Calibration uses three known elements

Clause 5.2 requires special care in calibrating the high-impedance setup. The calibration uses a short circuit or low-value resistor, a resistor of 25 ohm or 50 ohm nominal, and an open circuit or 10 pF nominal capacitor. This calibration step is the basis for correcting the measured voltages before calculating crystal impedance.

fL is found by searching for the reactance balance point

Clause 5.2 describes the measurement principle: the crystal impedance is calculated from the corrected voltages, and fL is the lower frequency where the crystal reactance equals the negative of the load-capacitance reactance. In practice, the network analyzer is used to find the frequency at which the reactance condition is satisfied.

Drive level at fL is corrected to match series resonance conditions

Clause 5.2(g) explains that the drive level at load resonance is lower than at series resonance because the reactance is high. The method therefore includes a correction measurement so the same drive level can be achieved for comparison. This matters when the user wants a result that is consistent with the series-resonance condition.

Error evaluation and limits are part of the method

Clause 5.3 discusses measurement accuracy, reproducibility, comparison with the manual method, and limitations. The document notes that noise affects reproducibility, that smaller IF filter bandwidths and averaging can improve results, and that the method is not to be used for ageing measurements or for load resonance in the temperature range. It also warns that activity dips can make results unacceptable and that errors become large when CL is small.

Annex A keeps the older manual method for reference. It covers physical load capacitors, zero phase π-network measurement, calibration of the load capacitor, and error analysis for the manual approach.

What terms does SIST EN IEC 60444-11:2026 define?

The document uses the terms and definitions from IEC 60122-1. The following terms are central to understanding the method:

• Load resonance frequency fL - The lower of the two frequencies where the crystal-unit combination is resistive with the specified load.
• Effective load capacitance CLeff - The load capacitance value derived from the crystal reactance at the nominal frequency.
• Figure of merit M - A parameter from IEC 60122-1 used here to set the applicability range of the method.
• Reference plane - The electrical point for measurement setup definition, taken from IEC 60444-5 practice.
• Zero phase π-network - The measurement network used for crystal testing and correction in the manual and related methods.
• Pulling sensitivity S - The sensitivity used when relating load-capacitance error to frequency error.

Who uses SIST EN IEC 60444-11:2026?

SIST EN IEC 60444-11:2026 is used by manufacturers of quartz crystal units, test laboratories, and engineers working on frequency-control components. It is also relevant to quality managers and buyers who need comparable test results for incoming inspection, qualification, or supplier comparison.

In practice, users apply it when they need a repeatable measurement of load resonance frequency or effective load capacitance without relying on physical load capacitors. That makes it useful in crystal testing, product characterization, and correlation to oscillator applications.

What changed in SIST EN IEC 60444-11:2026 from the previous edition?

This second edition cancels and replaces the first edition published in 2010, and EN IEC 60444-11:2026 supersedes EN 60444-11:2010 and its amendments and corrigenda. The technical changes stated in the document are:

• key content of withdrawn IEC TR 60444-4 is reproduced as Annex A
• some formulae from the first edition have been corrected

Which standards are used with SIST EN IEC 60444-11:2026?

The document names these related standards and companion parts:

• IEC 60122-1:2002 / AMD1:2017 - provides the generic specification for quartz crystal units and the terms used in this part.
• IEC 60444-1:1986 / AMD1:1999 - provides the basic zero phase π-network method and supports the reference concepts used in the measurement setup.
• IEC 60444-5:1995 - provides automatic network analyzer techniques and error correction, which are the technical basis for this part.
• IEC 60444-2 - is cited in Annex A for the phase offset method used for motional capacitance measurement.
• IEC 60122-2 - is cited in Annex A as a guide to the use of quartz crystal units.
• IEC TR 60444-4:1998 - the withdrawn manual-method report whose main content is retained in informative Annex A.

What does the SIST EN IEC 60444-11:2026 document contain?

The main body contains the measurement model, calibration approach, formulas for calculating crystal impedance, fL, and CLeff, and an error evaluation section. It also includes figures showing admittance, reactance behavior near resonance, drive level, and measurement error trends.

Annex A contains the manual measurement circuit, the physical load-capacitor design and insertion method, calibration and measurement steps for the capacitor, and a detailed error analysis with formulas and figures. The bibliography lists comparison papers and the supporting IEC references used by the document.

SLOVENSKI STANDARD
01-julij-2026
Nadomešča:
SIST EN 60444-11:2011
Meritev parametrov kvarčnokristanih enot - 11. del: Standardne metode za
ugotavljanje obremenitvene resonančne frekvence fL in efektivne obremenitvene
kapacitivnosti CLeff z uporabo tehnik z avtomatičnim omrežnim analizatorjem in
popravljanjem napak (IEC 60444-11:2026)
Measurement of quartz crystal unit parameters - Part 11: Standard method for the
determination of the load resonance frequency fL and the effective load capacitance
CLeff using automatic network analyzer techniques and error correction (IEC 60444-
11:2026)
Messung von Schwingquarz-Parametern - Teil 11: Standardverfahren zur Bestimmung
der Lastresonanzfrequenz fL und der effektiven Lastkapazität CLeff mit automatischer
Netzwerkanalysatortechnik und Fehlerkorrektur (IEC 60444-11:2026)
Mesure des paramètres unitaires quartz - Partie 11: Méthode standard pour la
détermination de la fréquence de résonance de charge fl et de la capacité de charge
effective cleff à l'aide de techniques d'analyseur de réseau automatiques et de correction
d'erreur (IEC 60444-11:2026)
Ta slovenski standard je istoveten z: EN IEC 60444-11:2026
ICS:
31.140 Piezoelektrične naprave Piezoelectric devices
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 60444-11

NORME EUROPÉENNE
EUROPÄISCHE NORM June 2026
ICS 31.140 Supersedes EN 60444-11:2010
English Version
Measurement of quartz crystal unit parameters - Part 11:
Standard method for the determination of the load resonance
frequency f and the effective load capacitance C using
L Leff
automatic network analyzer techniques and error correction
(IEC 60444-11:2026)
Mesure des paramètres des résonateurs à quartz - Partie Messung von Schwingquarz-Parametern - Teil 11:
11: Méthode normalisée pour la détermination de la Standardverfahren zur Bestimmung der
fréquence de résonance avec capacité de charge f et de la Lastresonanzfrequenz f und der effektiven Lastkapazität
L L
capacité de charge effective C à l'aide de techniques C mit automatischer Netzwerkanalysatortechnik und
Leff Leff
d'analyseur de réseau automatiques et de correction Fehlerkorrektur
d'erreur (IEC 60444-11:2026)
(IEC 60444-11:2026)
This European Standard was approved by CENELEC on 2026-05-27. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60444-11:2026 E

European foreword
The text of document 49/1489/CDV, future edition 2 of IEC 60444-11, prepared by TC 49
"Piezoelectric, dielectric and electrostatic devices and associated materials for frequency control,
selection and detection" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 60444-11:2026.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-06-30
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-06-30
document have to be withdrawn
This document supersedes EN 60444-11:2010 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 60444-11:2026 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 60122-2 NOTE Approved as EN IEC 60122-2
IEC 60444-2 NOTE Approved as EN 60444-2
IEC 60444-5:1995 NOTE Approved as EN 60444-5:1997 (not modified)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60122-1 2002 Quartz crystal units of assessed quality - Part 1: EN 60122-1 2002
Generic specification
+ A1 2017 + A1 2018
IEC 60444-1 1986 Measurement of quartz crystal unit parameters EN 60444-1 1997
by zero phase technique in a pi-network - Part 1:
Basic method for the measurement of resonance
frequency and resonance resistance of quartz
crystal units by zero phase technique in a pi-
network
+ A1 1999 + A1 1999
IEC 60444-11 ®
Edition 2.0 2026-04
INTERNATIONAL
STANDARD
Measurement of quartz crystal unit parameters -
Part 11: Standard method for the determination of the load resonance frequency
f and the effective load capacitance C using automatic network analyzer
L Leff
techniques and error correction
ICS 31.140  ISBN 978-2-8327-1199-6

IEC 60444-11:2026-04(en)
IEC 60444-11:2026 © IEC 2026
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 General concepts . 6
4.1 Load resonance frequencies f and f . 6
Lr La
4.2 Effective load capacitance C . 7
Leff
5 Reference plane and test conditions . 8
5.1 General . 8
5.2 Principle of measurement . 8
5.3 Evaluation of errors. 12
5.3.1 General comments . 12
5.3.2 Accuracy of measurement . 12
5.3.3 Reproducibility . 13
5.3.4 Comparison with the manual method . 15
5.3.5 Limitations . 15
Annex A (informative) Manual measuring method of the load resonance frequency f
L
and load resonance resistance R using physical load capacitance . 16
L
A.1 General . 16
A.2 Measuring circuit . 16
A.2.1 The measuring circuit of a zero phase π-network system . 16
A.2.2 An outline description . 16
A.2.3 Load capacitor specification . 17
A.3 Method of measurement . 17
A.3.1 Initial adjustment . 17
A.3.2 The method for the measurement of load resonance frequency and
resistance . 17
A.4 Load capacitor design . 17
A.4.1 Mechanical features . 17
A.4.2 Insertion into π-network . 18
A.4.3 Calibration and measurement of load capacitors . 20
A.5 Measurement errors . 21
A.5.1 General . 21
A.5.2 Main sources of measurement errors . 21
A.5.3 Effects of the frequency/temperature characteristics of the crystal unit . 22
A.5.4 Accuracy of the frequency measurements . 22
A.6 Analysis of errors . 22
A.6.1 Measurement error of load resonance frequency f . 22
L
A.6.2 Measurement error of load resonance resistance R . 23
L
A.6.3 Measurement errors of C . 24
Bibliography . 27

Figure 1 – Admittance of a quartz crystal unit . 7
IEC 60444-11:2026 © IEC 2026
Figure 2 – X as a function of frequency (solid line) in the vicinity of f . 10
C L
Figure 3 – P as level of drive of a crystal in a π-network versus df/f as frequency . 11
eff nom
Figure 4 – Error of the load resonance frequency due to the inaccuracy of the
measured voltages (dashed line) and the calibration resistances (soft line) . 13
Figure 5 – Error of the load resonance frequency due to the change of the setting C
L
for the same crystal as in Figure 4 . 13
Figure 6 –Error of the load resonance frequency due to noise of V as the measured
C
voltages . 14
Figure 7 – Error of load resonance frequency f at different C for typical equivalent
L L
parameters of quartz crystal units . 14
Figure A.1 – Typical load capacitor with carrier . 18
Figure A.2 – Method of insertion of load capacitor into π-network . 19
Figure A.3 – Circuit diagram of π-network including load capacitor C . 20
L
Figure A.4 – Load capacitance inaccuracy as a function of frequency, for a load
capacitance of 30 pF inclusive of calibration inaccuracy and residual inductance
effects (worst case situation) . 22
Figure A.5 – Relative measurement error of f versus crystal pulling sensitivity for
L
various frequencies at a load capacitance of 30 pF . 23
Figure A.6 – Relative measurement error of R versus frequency, for
L
various values of C . 23
L
Figure A.7 – Relative measurement error of C as a function of frequency. 24
Figure A.8 – Relative measurement error of C as a function of C for various
1 1
frequency measurement errors C = 5 pF; C = 15 pF; C = 30 pF . 25
o L1 L2
Figure A.9 – Relative measurement error of C as a function of C for various values
1 1
of quality factor Q C = 3 pF; C = 15 pF; C = 30 pF . 26
o L1 L2
IEC 60444-11:2026 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Measurement of quartz crystal unit parameters -
Part 11: Standard method for the determination of the load resonance
frequency f and the effective load capacitance C using automatic
L Leff
network analyzer techniques and error correction

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
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
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
misinterpretation by any end user.
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
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 60444-11 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 second edition cancels and replaces the first edition published in 2010. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) key content of withdrawn IEC TR 60444-4 is reproduced as Annex A;
b) some formulae in the first edition have been corrected.
IEC 60444-11:2026 © IEC 2026
The text of this International Standard is based on the following documents:
Draft Report on voting
49/1489/CDV 49/1515/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/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 webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC 60444-11:2026 © IEC 2026
INTRODUCTION
This part of IEC 60444 defines the measuring method of load resonance frequency f using
L
automatic network analyzer techniques.
At the same time, even though IEC TR 60444-4 [8] specifying the manual measuring method
has been withdrawn, the main contents of the manual measuring method remain as Annex A
for the user's convenience. However, in case of dispute, the standard method as described
below should be used as reference.
The figure of merit M, according to IEC 60122-1:2002, Table 1, is expressed in the following
formula:
Q 1
M
(1)
r ωC R
This gives good results in a frequency range up to 200 MHz. This method allows the calculation
of load resonance frequency offset ∆f , frequency pulling range ∆f ∆f and pulling sensitivity
L L1, L2
S as described in IEC 60122-1:2002, 2.2.31. This measurement technique avoids the use of
physical load capacitors, and allows higher accuracy, better reproducibility and correlation to
the application. It extends the upper frequency limit from 30 MHz by the manual method to
200 MHz approximately. This method is based on the error-corrected measurement technique
of IEC 60444-5 [9] and therefore allows the measurement of f and C together with the
L Leff
determination of the equivalent crystal parameters in one sequence without changing the test
fixture.
With this method the frequency f is searched where the reactance X of the crystal has the
L C
opposite value of the reactance of the load capacitance.
XX=−=
(2)
C CL
ωC
LL
Furthermore, this method allows to determine the effective load capacitance C at the nominal
Leff
frequency f
nom.
___________
Numbers in square brackets refer to the Bibliography.
= =
IEC 60444-11:2026 © IEC 2026
1 Scope
This part of IEC 60444 defines the standard method of measuring load resonance frequency f
L
at the nominal value of C , and the determination of the effective load capacitance C at the
L Leff
nominal frequency for crystals with the figure of merit M > 4.
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 60122-1:2002, Quartz crystal units of assessed quality - Part 1: Generic specification
IEC 60122-1:2002/AMD1:2017
IEC 60444-1:1986, Measurement of quartz crystal unit parameters by zero phase technique in
a pi-network - Part 1: Basic method for the measurement of resonance frequency and resonance
resistance of quartz crystal units by zero phase technique in a pi-network
IEC 60444-1:1986/AMD1:1999
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60122-1 apply.
ISO and IEC maintain terminology 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
4 General concepts
4.1 Load resonance frequencies f and f
Lr La
As can be seen in Figure 1, there are two intersection frequencies where XX= − , f with
C CL Lr
high admittance (low impedance) and f with low admittance (high impedance).
La
The load resonant frequency f is one of the two frequencies of a crystal unit in association with
L
a series or with a parallel load capacitance, at which the electrical admittance (respectively
impedance) of the combination is resistive. The load resonance frequency f is the lower of the
L
two frequencies.
In a first approximation f can be calculated by:
L
f =
S (3)
2π LC
IEC 60444-11:2026 © IEC 2026
 
C
ff≈+ 1
  (4)
L S
 
2 CC+
( )
0L
 
NOTE f is the load resonance frequenc
...