IEC 60444-6:2021
(Main)Measurement of quartz crystal unit parameters - Part 6: Measurement of drive level dependence (DLD)
Measurement of quartz crystal unit parameters - Part 6: Measurement of drive level dependence (DLD)
IEC 60444-6:2021 applies to the measurements of drive level dependence (DLD) of quartz crystal units. Two test methods (A and C) and one referential method (B) are described. “Method A”, based on the p-network according to IEC 60444-5, can be used in the complete frequency range covered by this part of IEC 60444. “Reference Method B”, based on the p-network or reflection method according to IEC 60444-5 or IEC 60444-8 can be used in the complete frequency range covered by this part of IEC 60444. “Method C”, an oscillator method, is suitable for measurements of fundamental mode crystal units in larger quantities with fixed conditions.
NOTE The measurement methods specified in this document are not only applicable to AT-cut, but also to other crystal cuts and vibration modes, such as doubly rotated cuts (IT,SC) and to tuning fork crystal units (by using a high impedance test fixture). This edition includes the following significant technical changes with respect to the previous edition:
- some equations have been removed and corrected;
- 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.
Mesure des paramètres des résonateurs à quartz - Partie 6: Mesure de la dépendance du niveau d’excitation (DNE)
L’IEC 60444-6:2021 s’applique aux mesures de la dépendance du niveau d’excitation (DNE) des résonateurs à quartz. Deux méthodes d’essai (A et C) et une méthode de référence (B) sont décrites. La méthode A, basée sur le réseau en p conformément à l’IEC 60444-5, peut être utilisée dans la plage de fréquences complète couverte par la présente partie de l’IEC 60444. La méthode de référence B, basée sur le réseau en p ou sur la méthode de réflexion conformément à l’IEC 60444-5 ou à l’IEC 60444-8, peut être utilisée dans la plage de fréquences complète couverte par la présente partie de l’IEC 60444. La méthode C, une méthode avec un oscillateur, est adaptée pour les mesures de résonateurs sur le mode fondamental en plus grandes quantités avec des conditions fixes. Cette édition inclut les modifications techniques majeures suivantes par rapport à l’édition précédente:
- certaines équations ont été supprimées ou corrigées;
- il est spécifié dans la note du Domaine d’application que les méthodes de mesure spécifiées dans le présent document ne s’appliquent pas uniquement à la coupe AT, mais aussi à d’autres coupes de cristaux et à d’autres modes de vibration.
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IEC 60444-6 ®
Edition 3.0 2021-09
REDLINE VERSION
INTERNATIONAL
STANDARD
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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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rights. IEC shall not be held responsible for identifying any or all such patent rights.
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 www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/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. Also, the
specifications based on the matters arranged in the Stanford meeting in June, 2011 are taken
into consideration.
– 6 – IEC 60444-6:2021 RLV © IEC 2021
MEASUREMENT OF QUARTZ CRYSTAL UNIT PARAMETERS –
Part 6: Measurement of drive level dependence (DLD)
1 Scope
This part of IEC 60444 applies to the measurements of drive level dependence (DLD) of quartz
crystal units. Two test methods (A and C) and one referential method (B) are described. “Method
A”, based on the π-network according to IEC 60444-1 IEC 60444-5, can be used in the complete
frequency range covered by this part of IEC 60444. “Reference Method B”, based on the π-
network or reflection method according to IEC 60444-1, IEC 60444-5 or IEC 60444-8 can be
used in the complete frequency range covered by this part of IEC 60444. “Method C”, an
oscillator method, is suitable for measurements of fundamental mode crystal units in larger
quantities with fixed conditions.
NOTE The measurement methods specified in this document are not only applicable to AT-cut, but also to other
crystal cuts and vibration modes, such as doubly rotated cuts (IT,SC) and to tuning fork crystal units (by using a high
impedance test fixture).
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 60444-1, Measurement of quartz crystal unit parameters by zero phase technique in a π-
network – Part 1: Basic method for the measurement of resonance frequency and resonance
resistance of quartz crystal units by zero phase technique in a π-network
IEC 60444-5, Measurement of quartz crystal unit parameters – Part 5: Methods for the
determination of equivalent electrical parameters using automatic network analyzer techniques
and error correction
IEC 60444-8, Measurement of quartz crystal unit parameters – Part 8: Test fixture for surface
mounted quartz crystal units
3 Terms and definitions
No terms and definitions are listed in this document.
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
4 DLD effects
4.1 Reversible changes in frequency and resistance
Reversible changes are changes in frequency and resistance occurring under the same drive
levels after repeated measurements made alternatively at low and high levels, or after
continuous or quasi-continuous measurements from the lowest to the highest level and back, if
these changes remain within the limits of the measurement accuracy.
4.2 Irreversible changes in frequency and resistance
Irreversible changes are significant changes in frequency and/or resistance occurring at low
level after an intermediate measurement at high level e.g. when a previously high resistance at
low level has changed in the repeated measurement to a low resistance. Especially, when the
crystal unit has not been operated for several days, its resistance may have changed back to a
high value when operated again at a lower level. Greater attention should be paid to the
irreversible effect since it can significantly impair the performance of devices, which are
operated only sporadically.
4.3 Causes of DLD effects
Whereas the mostly reversible effects are due to excessive crystal drive level, the irreversible
effects are due to production, especially to imperfect production techniques. Examples of
causes are:
– particles on the resonator surface (partly bound by oils, cleaning agents, solvents or bound
electro-statically);
– mechanical damage of the resonator (e.g. fissures due to excessively coarse lapping
abrasive which may increase in size);
– gas and oil inclusions in the electrodes (e.g. due to a poor vacuum or an inadequate coating
rate during evaporation);
– poor contacting of the electrodes at the mounting (e.g. the conductive adhesive has an
inadequate metal component, was insufficiently baked out or was overheated; also
excessive contact resistance between the conductive adhesive and the electrodes or
mounting);
– mechanical stresses between mounting, electrodes and quartz element.
5 Drive levels for DLD measurement
For the DLD measurement, a low and a high level of drive (and possibly further levels) are
applied. The high level is the nominal drive level, which should be equal to the level in the
application at its steady state.
It should be noted that this level should be below the maximum applicable level that is derived
in Annex A. If not specified, a standard value for the crystal current of 1 mA, corresponding to
the velocity v max = = 0,2 m/s v = 0,2 m/s for AT-cut crystal units, shall be used. The drive
max
level in watt is then calculated with the mean value of the specified maximum and minimum
resistances.
The minimum drive level occurring at the start-up of an oscillator can be determined only in a
few cases by active or passive measuring methods due to the noise limits of the measuring
instruments for measurements according to IEC 60444-1 IEC 60444-5, at approximately 1 nW
or 10 μA (depending on the equipment, the lowest power value can be reduced to 0,1 nW or
1 μA).
A velocity v max = 0,01 m/s v = 0,01 m/s, corresponding to 50 μA for AT-cut crystals, has
max
proved to be practical value for π-network measurements (see “Method A”).
Two methods and one referential method of DLD measurement are described below.
“Method A” is based on the π-network method according to IEC 60444-1 IEC 60444-5, which
can be used in the complete frequency range covered by this document. It allows the fast
selection of drive level sensitive quartz crystal units by a sequence of three measurements. The
– 8 – IEC 60444-6:2021 RLV © IEC 2021
allowed variation of the series resonance resistances given in Figure 1 is based on long-term
examinations of crystal units of different manufacturers and proved to be a reliable indicator for
crystal units showing start-up problems. If necessary, this method should also be extended by
measuring a large number of different drive levels. However, in practice, this is not necessary
in most cases (see 6.1).
In the industrial area, there are some commercially available crystal test systems like Saunders
250B or Kolinker KH1820 . Their software offers several variants for measuring DLD.
“Method B” is used for devices where strict oscillation start-up requirements have to be fulfilled
and for high reliability devices.
“Method C” as shown in Annex B is an oscillator method, which is especially suitable for
measuring fundamental mode crystal units in larger quantities with fixed measurement
conditions (maximum drive level, R max R , ) in an economical way.
1 max
r
If the proposed measurement techniques are not sufficient in special cases, the user should
have an original oscillator with slightly reduced feedback or an original filter.
“Method B” is stricter than “Method A”.
“Method B” is based on the π-network method or reflection method according to IEC 60444-1,
IEC 60444-5 or IEC 60444-8, which can be used in the complete frequency range covered by
this document.
Recommendation: These methods can be used for all types of crystals, however:
– “Method A” is recommended for filter and oscillator crystals;
– “Method B” is recommended for applications with strict start-up conditions, for high reliability
and for high stability applications. It is the reference method for failure analysis etc.;
– “Method C” in Annex B is a go/no-go measurement technique for oscillator crystals.
6 Test methods
6.1 Method A (fast standard measurement method)
6.1.1 Testing at two drive levels
Testing is performed at low and high drive levels as described in Clause 3 5 with measurements
of series resonance frequency and resistance according to IEC 60444-1 IEC 60444-5. The
tolerances are ± 10 % for the levels of current and ± 20 % for those of power.
a) Storage for at least one day at 105 °C and after that at least 2 hours at room temperature
or, storage for one week at room temperature.
b) The temperature should be kept constant during the measurement (in accordance with
IEC 60444-1 and IEC 60444-5).
f = f RR=
c) Measurement at low drive level (10 µA): f = f R = R , .
, s s1 11
r r1 r 11
f = f RR=
d) Measurement at high drive level (1 mA): f = f R = R , .
, ss2 1 12
r r2 r 12
f = f RR=
e) Measurement at low drive level (10 µA): f = f , R = R ss3 , 1 13 .
r r3 r 13
___________
Saunders 250B and Kolinker KH1820 are examples of suitable products available commercially. This information
is given for the convenience of users of this document and does not constitute an endorsement by IEC of these
products.
γ
e) Calculation of γ = RR . The value of γ shall be smaller than the maximum value of
12 11 12 12
given by the line drawn in Figure 1 (abscissa = R ).
-6
g) The tolerable frequency change f − f ff− shall be 5 × 10 × f f unless
r2 r1 ss21 r1 s1
otherwise specified in the detail specification.
g) Calculation of γ = RR . The value of γ shall be smaller than (γ +12) , where the value
13 11 13 13
γ
of is taken from Figure 1 (abscissa = R ).
-6
i) The tolerable frequency change f − f ff− shall be 2,5 × 10 × f f , unless
r3 r1 ss31 r1 s1
otherwise specified in the detail specification.
j) The resistance value shall not exceed the maximum value given by the detail specification
at any drive levels.
6.1.2 Testing according to specification
Testing is performed at low to high drive levels and back again to low level as described in 6.1.1.
These and, if necessary, further levels with their tolerances, the permissible deviations of the
frequency and resistance as well as storage conditions shall be specified in the detail
specification.
NOTE The given γ -curve was verified by results obtained over many years of experience with crystal units for
many oscillator types. In most cases, there will be no trouble in start-up, but in critical oscillator configurations,
problems may could occur. As it is not possible to manufacture crystal units, which have a constant resistance at
any drive level, the proposed ϒ-curve gives tolerable relations.
Definition of drive level values can be agreed between manufacturer and customer.
Use the nominal drive level of the detail specification as value for the high drive level. For
measurement at very high drive levels, an additional amplifier may be required.
– 10 – IEC 60444-6:2021 RLV © IEC 2021
Figure 1 – Maximum tolerable resistance ratio γ for the drive
level dependence as a function of the resistances R or R R or R
r2 r3 12 13
NOTE 2 The equation for the recommended drive level (if not otherwise specified in the data sheet) is as follows.
Details can be found in Annex A of IEC 60122-2-1:1991, Amendment 1:1993.
The maximum drive level recommended to be selected so that with a further increase of the
drive level by 50 %, the resistance does not increase reversibly by more than 10 % or the
-6
frequency changes by more than 0,5 × 10 .
nA
I = K ⋅
q
f
where
I is the recommended current for oscillating state;
q
n is the overtone order, fundamental vibration mode, n = 1;
A is the electrode size in mm ;
f is the frequency in MHz;
-2 -1/2
K is 0,35 mA ⋅ mm ⋅ s .
6.2 Method B (Multi-level reference measurement method)
Testing is performed at low and high drive levels as described in Clause 3 5 with measurements
of resonance frequency and resistance according to IEC 60444-5. The tolerances are ±10 %
for the levels of current and ±20 % for those of power.
a) Storage for at least one day at 105 °C and after that at least 2 hours at room temperature
or storage for one week at room temperature.
NOTE If considered as necessary, the customer and the maker agree on a higher temperature and a longer
duration for the storage before DLD measurement.
b) The temperature should be kept constant during the measurement IAW (in accordance with
IEC 60444-5).
c) The drive level is applied by two types of measurement units. It should also be applied
sequentially starting from the lowest to the highest value and then back to the lowest value.
A definition for the unit of drive levels shall be specified between the crystal manufacturer
and the user.
1) When the unit of a drive level is mA;
Measurement drives level: from 2 μA to nominal drive level in at least 7 levels which are
logarithmically scaled. (Refer to the equation given under item f)).
2) When the unit of a drive level is μW;
Measurement drives level: From 2 nW to nominal drive level in at least 7 levels which
are logarithmically scaled. (Refer to the equation given under item f)).
d) The maximum frequency excursion over all drive levels shall be less than the following
specifications.
fi ,,− fi
( ) ( )
ssmax min −6
<×5 10
1)
f
NOM
or,
fi ,,− fi
( ) ( )
ssmax min
<×0.5 f
2)
ADJ
f
NOM
where
fi , is the maximum value for frequency measurement values with i = 1 to 2⋅N-1
( )
s max
drive levels;
is the minimum value for frequency measurement values with i = 1 to 2⋅N-1
fi ,
( )
s min
drive levels;
f is the nominal frequency;
NOM
f is the practical specification for frequency adjustment tolerance.
ADJ
e) The maximum ratio of resistance change and the maximum resistance over drive levels shall
be as the following specifications:
Ri( ),
1 max
< γ
1)
Ri ,
( )
min
and
R (11) (γ + )
2) <
RN21⋅− 2
( )
and
3)
Ri , < R
( )
1 max 1,max
where,
Ri , is the maximum value for resistance measurement values with i = 1 to 2⋅N-
( )
1 max
1 drive levels;
is the minimum value for resistance measurement values with i = 1 to 2⋅N-1
Ri( ),
min
drive levels;
R , is the maximum resistance, specified by the detail specification;
1 max
is the resistance ratio.
γ
f) The N drive levels should be logarithmically scaled, i.e. DL DL× K . The equation for
NN+1
the recommended drive level (if not otherwise specified in the data sheet) is as follows:
=
– 12 – IEC 60444-6:2021 RLV © IEC 2021
N −1
DL
max
K =
DL
min
g) A larger number of drive levels may be necessary in special applications, e.g. those caused
by mechanical coupling with nonlinear spurious resonances (dips) and for failure analysis.
Annex A
(normative)
Relationship between electrical drive level and
mechanical displacement of quartz crystal units
The power loss of a crystal unit in watt is given by:
P = I ⋅ R
c 1
where
I is the current through the crystal unit in amperes;
R is the motional resistance in ohms.
The reactive power is given by:
I
P = = P ⋅ Q
B c
2πf ⋅ C
where
f is the resonance frequency in hertz;
C is the motional capacitance in farads;
Q is the quality factor.
The electric energy in watt seconds is given by:
P
I
B
A = =
EL
f
2πf ⋅ C
The mechanical energy of a crystal unit can be represented by the following terms:
A = A + A + A + A
mech kin elast pot B
A = ⋅ ρ ⋅V ⋅ v (kinetic energy)
kin
A = ⋅ c ⋅V ⋅ x (elastic energy)
elast
2 2
A = ⋅ ρ ⋅V ⋅ s ⋅ (2πf ) (potential energy)
pot
1 ρ ⋅V ⋅ b
A = ⋅
B (acceleration work)
(2πf )
ρ = 2 650 kg/m (density)
where
V is the volume of the oscillating area in cubic meters (m );
– 14 – IEC 60444-6:2021 RLV © IEC 2021
v = ds/dt is the velocity in meters per seconds (m/s);
c is the modulus of elasticity of the mode of vibration (for AT-cut crystal units,
' 10
c = c = 2,93 × 10 N/m )
x = ∆ll is the elongation;
s is the excursion from rest position in metres;
2 2 2
b = d s/dt is the acceleration in meters per square seconds (m/s );
n is the overtone order.
The volume V can be approximately calculated from the electrode area F and the electrode
EL
spacing d .
From the static capacitance:
F
EL
C = ε ⋅ε ⋅ = C
e r 0 0
d
where
ε is the relative dielectric constant of AT-cut quartz material and is equal to 4,54;
r
−12
ε is the electric field constant and is equal to 8,86 ×10 F/m;
N N
is the frequency constant equal to f ⋅(d / n). = 1 665 Hz⋅m for AT-cut crystal units;
n is the overtone order.
The following is obtained:
C nN⋅
V ≈⋅
εε⋅
f
r0
and the maximum current from the maximum velocities, elongations, excursions or
accelerations of the mechanical vibrations:
π ⋅ ρ ⋅ N
I = K ⋅ n ⋅ C ⋅ C ⋅ v where K =
max 1 0 1 max
ε ⋅ε
r 0
π ⋅ c ⋅ N
I = K ⋅ n ⋅ C ⋅ C ⋅ x where K =
max 2 0 1 max
ε ⋅ε
r 0
3 2
4 ⋅π ⋅ ρ ⋅ N
I = K ⋅ n ⋅ C ⋅ C ⋅ s where K =
max 3 0 1 max
ε ⋅ε
r 0
b ρ ⋅ N
max
I = K ⋅ n ⋅ C ⋅ C ⋅ where K =
max 4 0 1 4
f 4 ⋅π ⋅ε ⋅ε
r 0
π ⋅ ρ ⋅ N
I Kn⋅⋅ C⋅C⋅v K =
where
1 0 1 1
ε ⋅ε
r 0
=
π ⋅ c ⋅ N
I K⋅ n⋅ CC⋅ ⋅ x where K =
2 0 1 2
ε ⋅ε
r 0
3 2
4 ⋅π ⋅ ρ ⋅ N
I K⋅ n⋅ C⋅C⋅⋅sf where K =
3 0 1 3
ε ⋅ε
r 0
b ρ ⋅ N
I K⋅ n⋅ CC⋅ ⋅ where K =
4 0 1 4
f 4 ⋅π ⋅ε ⋅ε
r 0
For non-convex AT-cut crystal units, the following also applies:
C C = γ = 200 ⋅ n
0 1
C
0 2
=γ≈⋅250 n
C
where
n is the overtone order.
The constant “250” fits well with the measurement value when it is used in the case of
miniaturized crystal units such as surface mounted crystals. On the other hand, in the case of
conventional crystal units, such as HU-6/U, HC-43/U, it is recommended to use “200” as the
constant.
The following is obtained with C = 5 pF for the currents:
I I
max,1 max,2
= 50 mA μA = 1 mA
v = 0,01 m/s v = 0,2 m/s
1 2
-6 -5
x = 1,8 × 10 x = 3,6 × 10
1 2
at f = 10 MHz:
-11 -9
s = 6,7 × 10 m s = 1,3 × 10 m
1 2
5 2 6 2
b = 2,6 × 10 m/s b = 5,3 × 10 m/s
1 1
at f = 100 MHz:
-12 -10
s = 6,7 × 10 m s = 1,3 × 10 m
1 2
6 2 7 2
b = 2,6 × 10 m/s b = 5,3 × 10 m/s
1 2
Depending on the frequency, quality factor and mode of vibration of the crystal unit and the
volume of the vibrating zone, maximum currents or levels result from limit considerations for
every type of a crystal unit. These shall not be exceeded when using these devices in oscillators
and filters.
=
=
=
– 16 – IEC 60444-6:2021 RLV © IEC 2021
The maximum drive level shall be selected so that with a further increase of the drive level by
50 %, the resistance does not increase reversibly by more than 10 % or the frequency changes
-6
by more than 0,5 × 10 .
Annex B
(normative)
Method C: DLD measurement with oscillation circuit
To detect the DLD effect over the whole drive level range, the method described in 6.1 is very
costly and is not applicable as a 100 % go/no-go test. The method proposed below tests the
crystal units on its maximum R during start-up in an economical manner. This method can be
r
applied as a 100 % final inspection as well as in a 100 % incoming inspection. It can also be
used as an instrument to judge whether the crystal unit meets the requirements on R R
rmax max
given in the detail specification.
The crystal unit in the oscillator can be represented as indicated in Figure B.1.
−R R
There will be no oscillation when the magnitude of the of the circuit is lower than of
osc r
the crystal unit.
During start-up, the R of the crystal unit may behave as shown in Figure B.2.
r
When measuring the crystal unit several times, the characteristic can shift slightly to the right
or to the left or it can flatten.
The ratio γ = R R may also differ from measurement to measurement. This ratio does not
r 2 r1
necessarily mean that the oscillator may stop working if a certain value of is reached. The
γ
most important aspect is the safety margin between the maximum occurring R of the crystal
r
R
unit and the value of of the oscillator circuit.
osc
It is recommended that the circuit should have a of because in the
−R ≥ 3 R
osc r max
temperature range, the R as well as −R can shift.
r max osc
During the start-up, the drive level will move from the low values (left side of the graphics in
Figure B.3) to the nominal drive level.
The principle of measurement is presented in Figure B.4.
The test set-up consists of a carefully designed crystal oscillator which can be considered as a
true negative resistance over a wide frequency range, a feedback network which limits the
power dissipation in the crystal unit to 1 mW and a detector circuit with an LED for visual
indication.
Figure B.1 – Insertion of a quartz crystal unit in an oscillator
– 18 – IEC 60444-6:2021 RLV © IEC 2021
Oscillation conditions:
• loop gain > 1, which means
−>RR
osc r
• feedback signal at oscillator input shall have correct phase.
Figure B.2 – Crystal unit loss resistance as a function of dissipated power
NOTE The ratio R R is not a reproducible value since the crystal unit curve slightly shifts at different
r 2 r1
measurement cycles.
The negative resistance (and with it the DLD reject level) of the oscillator can be changed by
connecting a positive resistor in series with the oscillator. In this manner, each value between
0 Ω and 200 Ω may be selected. Connecting a quartz crystal unit with a sufficiently low R value
r
between the test clamps, the oscillation will build up starting from the initial noise level
-16 -15
(approximately 10 W to 10 W) to its limiting point for 1 mW as shown in Figure B.5.
R
During the start-up, the of the crystal unit is continuously compared with a Calibrated-
rmax
R and the result is detected and transferred into a go/no-go decision.
osc
If the crystal unit under test shows a certain degree of DLD, it is possible that the oscillation
amplitude will not reach the 1 mW limiting point (point B in Figure B.6). In the example given in
Figure B.6, the build-up of the oscillation is terminated at a much lower level of drive (point A).
Normally in such cases, no oscillation is observed and only with very sensitive equipment can
some oscillation be detected.
If a crystal unit reaches the 1 mW level (point B), the LED indicator will light up. This means
that the quartz crystal unit’s resonance resistance did not exceed the DLD reject level during
the start-up.
The advantages of this measurement method are that it is fast, easy to calibrate, inexpensive
and it has a simple set-up. A detailed electrical diagram is shown in Figure B.7. The equipment
is commercially available.
Figure B.3 – Behaviour of the R of a quartz crystal unit
r
Figure B.4 – Block diagram of circuit system
– 20 – IEC 60444-6:2021 RLV © IEC 2021
Figure B.5 – Installed −R in scanned drive level range
osc
Figure B.6 – Drive level behaviour of a quartz crystal unit
if −R = 70 Ω is used as test limit in the Annex B test
osc
Figure B.7 – Principal schematic diagram of the go/no-go test circuit
– 22 – IEC 60444-6:2021 RLV © IEC 2021
Bibliography
IEC 60122-2-1:1991, Quartz crystal units for frequency control and selection – Part 2: Guide to
the use of quartz crystal units for frequency control and selection – Section one: Quartz crystal
units for microprocessor clock supply
Amendment 1:1993
IEC 60444-1, Measurement of quartz crystal unit parameters by zero phase technique in a π-
network – Part 1: Basic method for the measurement of resonance frequency and resonance
resistance of quartz crystal units by zero phase technique in a π-network
___________
IEC 60444-6 ®
Edition 3.0 2021-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Measurement of quartz crystal unit parameters –
Part 6: Measurement of drive level dependence (DLD)
Mesure des paramètres des résonateurs à quartz –
Partie 6: Mesure de la dépendance du niveau d’excitation (DNE)
– 2 – IEC 60444-6:2021 © 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
Annex A (normative) Relationship between electrical drive level and mechanical
displacement of quartz crystal units . 12
Annex B (normative) Method C: DLD measurement with oscillation circuit . 15
Bibliography . 20
γ
Figure 1 – Maximum tolerable resistance ratio for the drive level dependence as a
function of the resistances R or R . 9
12 13
Figure B.1 – Insertion of a quartz crystal unit in an oscillator . 15
Figure B.2 – Crystal unit loss resistance as a function of dissipated power . 16
Figure B.3 – Behaviour of the R of a quartz crystal unit . 17
r
Figure B.4 – Block diagram of circuit system . 17
Figure B.5 – Installed −R in scanned drive level range . 18
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 . 18
Figure B.7 – Principal schematic diagram of the go/no-go test circuit . 19
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEASUREMENT OF QUARTZ CRYSTAL UNIT PARAMETERS –
Part 6: Measurement of drive level dependence (DLD)
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 m
...
IEC 60444-6 ®
Edition 3.0 2021-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Measurement of quartz crystal unit parameters –
Part 6: Measurement of drive level dependence (DLD)
Mesure des paramètres des résonateurs à quartz –
Partie 6: Mesure de la dépendance du niveau d’excitation (DNE)
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IEC 60444-6 ®
Edition 3.0 2021-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Measurement of quartz crystal unit parameters –
Part 6: Measurement of drive level dependence (DLD)
Mesure des paramètres des résonateurs à quartz –
Partie 6: Mesure de la dépendance du niveau d’excitation (DNE)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.140 ISBN 978-2-8322-1014-4
– 2 – IEC 60444-6:2021 © 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
Annex A (normative) Relationship between electrical drive level and mechanical
displacement of quartz crystal units . 12
Annex B (normative) Method C: DLD measurement with oscillation circuit . 15
Bibliography . 20
γ
Figure 1 – Maximum tolerable resistance ratio for the drive level dependence as a
function of the resistances R or R . 9
12 13
Figure B.1 – Insertion of a quartz crystal unit in an oscillator . 15
Figure B.2 – Crystal unit loss resistance as a function of dissipated power . 16
Figure B.3 – Behaviour of the R of a quartz crystal unit . 17
r
Figure B.4 – Block diagram of circuit system . 17
Figure B.5 – Installed −R in scanned drive level range . 18
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 . 18
Figure B.7 – Principal schematic diagram of the go/no-go test circuit . 19
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEASUREMENT OF QUARTZ CRYSTAL UNIT PARAMETERS –
Part 6: Measurement of drive level dependence (DLD)
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
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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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
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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) 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.
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.
– 4 – IEC 60444-6:2021 © IEC 2021
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 www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/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.
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 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.
In this new edition, the concept of DLD in IEC 60444-6:2013 is maintained. However, the more
suitable contents for the user’s severe requirements have been introduced.
– 6 – IEC 60444-6:2021 © IEC 2021
MEASUREMENT OF QUARTZ CRYSTAL UNIT PARAMETERS –
Part 6: Measurement of drive level dependence (DLD)
1 Scope
This part of IEC 60444 applies to the measurements of drive level dependence (DLD) of quartz
crystal units. Two test methods (A and C) and one referential method (B) are described. “Method
A”, based on the π-network according to IEC 60444-5, can be used in the complete frequency
range covered by this part of IEC 60444. “Reference Method B”, based on the π-network or
reflection method according to IEC 60444-5 or IEC 60444-8 can be used in the complete
frequency range covered by this part of IEC 60444. “Method C”, an oscillator method, is suitable
for measurements of fundamental mode crystal units in larger quantities with fixed conditions.
NOTE The measurement methods specified in this document are not only applicable to AT-cut, but also to other
crystal cuts and vibration modes, such as doubly rotated cuts (IT,SC) and to tuning fork crystal units (by using a high
impedance test fixture).
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 60444-5, Measurement of quartz crystal unit parameters – Part 5: Methods for the
determination of equivalent electrical parameters using automatic network analyzer techniques
and error correction
IEC 60444-8, Measurement of quartz crystal unit parameters – Part 8: Test fixture for surface
mounted quartz crystal units
3 Terms and definitions
No terms and definitions are listed in this document.
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
4 DLD effects
4.1 Reversible changes in frequency and resistance
Reversible changes are changes in frequency and resistance occurring under the same drive
levels after repeated measurements made alternatively at low and high levels, or after
continuous or quasi-continuous measurements from the lowest to the highest level and back, if
these changes remain within the limits of the measurement accuracy.
4.2 Irreversible changes in frequency and resistance
Irreversible changes are significant changes in frequency and/or resistance occurring at low
level after an intermediate measurement at high level e.g. when a previously high resistance at
low level has changed in the repeated measurement to a low resistance. Especially, when the
crystal unit has not been operated for several days, its resistance may have changed back to a
high value when operated again at a lower level. Greater attention should be paid to the
irreversible effect since it can significantly impair the performance of devices, which are
operated only sporadically.
4.3 Causes of DLD effects
Whereas the mostly reversible effects are due to excessive crystal drive level, the irreversible
effects are due to production, especially to imperfect production techniques. Examples of
causes are:
– particles on the resonator surface (partly bound by oils, cleaning agents, solvents or bound
electro-statically);
– mechanical damage of the resonator (e.g. fissures due to excessively coarse lapping
abrasive which may increase in size);
– gas and oil inclusions in the electrodes (e.g. due to a poor vacuum or an inadequate coating
rate during evaporation);
– poor contacting of the electrodes at the mounting (e.g. the conductive adhesive has an
inadequate metal component, was insufficiently baked out or was overheated; also
excessive contact resistance between the conductive adhesive and the electrodes or
mounting);
– mechanical stresses between mounting, electrodes and quartz element.
5 Drive levels for DLD measurement
For the DLD measurement, a low and a high level of drive (and possibly further levels) are
applied. The high level is the nominal drive level, which should be equal to the level in the
application at its steady state.
It should be noted that this level should be below the maximum applicable level that is derived
in Annex A. If not specified, a standard value for the crystal current of 1 mA, corresponding to
the velocity v = 0,2 m/s for AT-cut crystal units, shall be used. The drive level in watt is
max
then calculated with the mean value of the specified maximum and minimum resistances.
The minimum drive level occurring at the start-up of an oscillator can be determined only in a
few cases by active or passive measuring methods due to the noise limits of the measuring
instruments for measurements according to IEC 60444-5, at approximately 1 nW or 10 μA
(depending on the equipment, the lowest power value can be reduced to 0,1 nW or 1 μA).
A velocity v = 0,01 m/s, corresponding to 50 μA for AT-cut crystals, has proved to be
max
practical value for π-network measurements (see “Method A”).
Two methods and one referential method of DLD measurement are described below.
“Method A” is based on the π-network method according to IEC 60444-5, which can be used in
the complete frequency range covered by this document. It allows the fast selection of drive
level sensitive quartz crystal units by a sequence of three measurements. The allowed variation
of the series resonance resistances given in Figure 1 is based on long-term examinations of
crystal units of different manufacturers and proved to be a reliable indicator for crystal units
showing start-up problems. If necessary, this method should also be extended by measuring a
large number of different drive levels. However, in practice, this is not necessary in most cases
(see 6.1).
– 8 – IEC 60444-6:2021 © IEC 2021
In the industrial area, there are some commercially available crystal test systems like Saunders
250B or Kolinker KH1820 . Their software offers several variants for measuring DLD.
“Method B” is used for devices where strict oscillation start-up requirements have to be fulfilled
and for high reliability devices.
“Method C” as shown in Annex B is an oscillator method, which is especially suitable for
measuring fundamental mode crystal units in larger quantities with fixed measurement
conditions (maximum drive level, R , ) in an economical way.
1 max
If the proposed measurement techniques are not sufficient in special cases, the user should
have an original oscillator with slightly reduced feedback or an original filter.
“Method B” is stricter than “Method A”.
“Method B” is based on the π-network method or reflection method according to IEC 60444-5
or IEC 60444-8, which can be used in the complete frequency range covered by this document.
Recommendation: These methods can be used for all types of crystals, however:
– “Method A” is recommended for filter and oscillator crystals;
– “Method B” is recommended for applications with strict start-up conditions, for high reliability
and for high stability applications. It is the reference method for failure analysis etc.;
– “Method C” in Annex B is a go/no-go measurement technique for oscillator crystals.
6 Test methods
6.1 Method A (fast standard measurement method)
6.1.1 Testing at two drive levels
Testing is performed at low and high drive levels as described in Clause 5 with measurements
of series resonance frequency and resistance according to IEC 60444-5. The tolerances are
± 10 % for the levels of current and ± 20 % for those of power.
a) Storage for at least one day at 105 °C and after that at least 2 hours at room temperature
or, storage for one week at room temperature.
b) The temperature should be kept constant during the measurement (in accordance with
IEC 60444-5).
f = f RR=
, .
c) Measurement at low drive level (10 μA): s s1 11
f = f RR=
d) Measurement at high drive level (1 mA): , .
ss2 1 12
f = f RR=
e) Measurement at low drive level (10 μA): , .
ss3 1 13
f) Calculation of γ = RR . The value of γ shall be smaller than the maximum value of γ
12 11 12 12
given by the line drawn in Figure 1 (abscissa = R ).
-6
g) The tolerable frequency change ff− shall be 5 × 10 × f unless otherwise specified
ss21 s1
in the detail specification.
h) Calculation of γ = RR . The value of γ shall be smaller than (γ +12) , where the value
13 11 13 13
γ
of is taken from Figure 1 (abscissa = R ).
___________
Saunders 250B and Kolinker KH1820 are examples of suitable products available commercially. This information
is given for the convenience of users of this document and does not constitute an endorsement by IEC of these
products.
-6
i) The tolerable frequency change ff− shall be 2,5 × 10 × f , unless otherwise
ss31 s1
specified in the detail specification.
j) The resistance value shall not exceed the maximum value given by the detail specification
at any drive levels.
6.1.2 Testing according to specification
Testing is performed at low to high drive levels and back again to low level as described in 6.1.1.
These and, if necessary, further levels with their tolerances, the permissible deviations of the
frequency and resistance as well as storage conditions shall be specified in the detail
specification.
NOTE The given γ -curve was verified by results obtained over many years of experience with crystal units for
many oscillator types. In most cases, there will be no trouble in start-up, but in critical oscillator configurations,
problems could occur. As it is not possible to manufacture crystal units, which have a constant resistance at any
drive level, the proposed ϒ-curve gives tolerable relations.
Definition of drive level values can be agreed between manufacturer and customer.
Use the nominal drive level of the detail specification as value for the high drive level. For
measurement at very high drive levels, an additional amplifier may be required.
Figure 1 – Maximum tolerable resistance ratio γ for the drive
level dependence as a function of the resistances R or R
12 13
The maximum drive level recommended to be selected so that with a further increase of the
drive level by 50 %, the resistance does not increase reversibly by more than 10 % or the
-6
frequency changes by more than 0,5 × 10 .
nA
I = K ⋅
q
f
– 10 – IEC 60444-6:2021 © IEC 2021
where
I is the recommended current for oscillating state;
q
n
is the overtone order;
A is the electrode size in mm ;
f is the frequency in MHz;
-2 -1/2
K is 0,35 mA ⋅ mm ⋅ s .
6.2 Method B (Multi-level reference measurement method)
Testing is performed at low and high drive levels as described in Clause 5 with measurements
of resonance frequency and resistance according to IEC 60444-5. The tolerances are ±10 %
for the levels of current and ±20 % for those of power.
a) Storage for at least one day at 105 °C and after that at least 2 hours at room temperature
or storage for one week at room temperature.
NOTE If considered as necessary, the customer and the maker agree on a higher temperature and a longer
duration for the storage before DLD measurement.
b) The temperature should be kept constant during the measurement IAW (in accordance with
IEC 60444-5).
c) The drive level is applied by two types of measurement units. It should also be applied
sequentially starting from the lowest to the highest value and then back to the lowest value.
A definition for the unit of drive levels shall be specified between the crystal manufacturer
and the user.
1) When the unit of a drive level is mA;
Measurement drives level: from 2 μA to nominal drive level in at least 7 levels which are
logarithmically scaled. (Refer to the equation given under item f)).
2) When the unit of a drive level is μW;
Measurement drives level: From 2 nW to nominal drive level in at least 7 levels which
are logarithmically scaled. (Refer to the equation given under item f)).
d) The maximum frequency excursion over all drive levels shall be less than the following
specifications.
fi ,,− fi
( ) ( )
ssmax min −6
1) <×5 10
f
NOM
or,
fi ,,− fi
( ) ( )
ssmax min
<×0.5 f
2)
ADJ
f
NOM
where
is the maximum value for frequency measurement values with i = 1 to 2⋅N-1
fi( ),
s max
drive levels;
fi , is the minimum value for frequency measurement values with i = 1 to 2⋅N-1
( )
s min
drive levels;
f is the nominal frequency;
NOM
f is the practical specification for frequency adjustment tolerance.
ADJ
e) The maximum ratio of resistance change and the maximum resistance over drive levels shall
be as the following specifications:
Ri ,
( )
1 max
< γ
1)
Ri( ),
min
and
R 11γ +
( ) ( )
2) <
RN(21⋅− ) 2
and
3)
Ri( ), < R
1 max 1,max
where,
Ri , is the maximum value for resistance measurement values with i = 1 to 2⋅N-
( )
1 max
1 drive levels;
is the minimum value for resistance measurement values with i = 1 to 2⋅N-1
Ri( ),
min
drive levels;
R , is the maximum resistance, specified by the detail specification;
1 max
is the resistance ratio.
γ
f) The N drive levels should be logarithmically scaled, i.e. DL DL× K . The equation for
NN+1
the recommended drive level (if not otherwise specified in the data sheet) is as follows:
N −1
DL
max
K =
DL
min
g) A larger number of drive levels may be necessary in special applications, e.g. those caused
by mechanical coupling with nonlinear spurious resonances (dips) and for failure analysis.
=
– 12 – IEC 60444-6:2021 © IEC 2021
Annex A
(normative)
Relationship between electrical drive level and
mechanical displacement of quartz crystal units
The power loss of a crystal unit in watt is given by:
P = I ⋅ R
c 1
where
I is the current through the crystal unit in amperes;
R is the motional resistance in ohms.
The reactive power is given by:
I
P = = P ⋅ Q
B c
2πf ⋅ C
where
f is the resonance frequency in hertz;
C is the motional capacitance in farads;
Q is the quality factor.
The electric energy in watt seconds is given by:
P I
B
A = =
EL
f
2πf ⋅ C
The mechanical energy of a crystal unit can be represented by the following terms:
A = ⋅ ρ ⋅V ⋅ v (kinetic energy)
kin
A = ⋅ c ⋅V ⋅ x (elastic energy)
elast
2 2
A = ⋅ ρ ⋅V ⋅ s ⋅ (2πf ) (potential energy)
pot
1 ρ ⋅V ⋅ b
A = ⋅
B (acceleration work)
(2πf )
ρ kg/m
= 2 650 (density)
where
V
is the volume of the oscillating area in cubic meters (m );
v = ds/dt is the velocity in meters per seconds (m/s);
c is the modulus of elasticity of the mode of vibration (for AT-cut crystal units,
' 10
c = c = 2,93 × 10 N/m )
x = ∆ll is the elongation;
s is the excursion from rest position in metres;
2 2 2
b = d s/dt is the acceleration in meters per square seconds (m/s );
n is the overtone order.
The volume V can be approximately calculated from the electrode area F and the electrode
EL
spacing d .
From the static capacitance:
F
EL
C = ε ⋅ε ⋅ = C
e r 0 0
d
where
ε is the relative dielectric constant of AT-cut quartz material and is equal to 4,54;
r
−12
ε is the electric field constant and is equal to 8,86 ×10 F/m;
N N
is the frequency constant equal to f ⋅(d / n). = 1 665 Hz⋅m for AT-cut crystal units;
n is the overtone order.
The following is obtained:
C nN⋅
V ≈⋅
εε⋅
f
r0
and the current from the velocities, elongations, excursions or accelerations of the mechanical
vibrations:
π ⋅ ρ ⋅ N
I Kn⋅⋅ C⋅C⋅v where K =
1 0 1 1
ε ⋅ε
r 0
π ⋅ c ⋅ N
I K⋅ n⋅ CC⋅ ⋅ x where K =
2 0 1 2
ε ⋅ε
r 0
3 2
4 ⋅π ⋅ ρ ⋅ N
I K⋅ n⋅ C⋅C⋅⋅sf where K =
3 0 1 3
ε ⋅ε
r 0
b ρ ⋅ N
I K⋅ n⋅ CC⋅ ⋅ where K =
4 0 1 4
f 4 ⋅π ⋅ε ⋅ε
r 0
For non-convex AT-cut crystal units, the following also applies:
C
=γ≈⋅250 n
C
where
n is the overtone order.
=
=
=
=
– 14 – IEC 60444-6:2021 © IEC 2021
The constant “250” fits well with the measurement value when it is used in the case of
miniaturized crystal units such as surface mounted crystals. On the other hand, in the case of
conventional crystal units, such as HU-6/U, HC-43/U, it is recommended to use “200” as the
constant.
The following is obtained with C = 5 pF for the currents:
I I
max,1 max,2
= 50 μA = 1 mA
v = 0,01 m/s v = 0,2 m/s
1 2
-6 -5
x = 1,8 × 10 x = 3,6 × 10
1 2
at f = 10 MHz:
-11 -9
s = 6,7 × 10 m s = 1,3 × 10 m
1 2
5 2 6 2
b = 2,6 × 10 m/s b = 5,3 × 10 m/s
1 1
at f = 100 MHz:
-12 -10
s = 6,7 × 10 m s = 1,3 × 10 m
1 2
6 2 7 2
b = 2,6 × 10 m/s b = 5,3 × 10 m/s
1 2
Depending on the frequency, quality factor and mode of vibration of the crystal unit and the
volume of the vibrating zone, maximum currents or levels result from limit considerations for
every type of a crystal unit. These shall not be exceeded when using these devices in oscillators
and filters.
Annex B
(normative)
Method C: DLD measurement with oscillation circuit
To detect the DLD effect over the whole drive level range, the method described in 6.1 is very
costly and is not applicable as a 100 % go/no-go test. The method proposed below tests the
crystal units on its maximum R during start-up in an economical manner. This method can be
r
applied as a 100 % final inspection as well as in a 100 % incoming inspection. It can also be
used as an instrument to judge whether the crystal unit meets the requirements on R given
max
in the detail specification.
The crystal unit in the oscillator can be represented as indicated in Figure B.1.
−R R
There will be no oscillation when the magnitude of the of the circuit is lower than of
osc r
the crystal unit.
During start-up, the R of the crystal unit may behave as shown in Figure B.2.
r
When measuring the crystal unit several times, the characteristic can shift slightly to the right
or to the left or it can flatten.
The ratio γ = R R may also differ from measurement to measurement. This ratio does not
r 2 r1
necessarily mean that the oscillator may stop working if a certain value of is reached. The
γ
most important aspect is the safety margin between the maximum occurring R of the crystal
r
R
unit and the value of of the oscillator circuit.
osc
It is recommended that the circuit should have a of because in the
−R ≥ 3 R
osc r max
temperature range, the R as well as −R can shift.
r max osc
During the start-up, the drive level will move from the low values (left side of the graphics in
Figure B.3) to the nominal drive level.
The principle of measurement is presented in Figure B.4.
The test set-up consists of a carefully designed crystal oscillator which can be considered as a
true negative resistance over a wide frequency range, a feedback network which limits the
power dissipation in the crystal unit to 1 mW and a detector circuit with an LED for visual
indication.
Figure B.1 – Insertion of a quartz crystal unit in an oscillator
– 16 – IEC 60444-6:2021 © IEC 2021
Oscillation conditions:
• loop gain > 1, which means
−>RR
osc r
• feedback signal at oscillator input shall have correct phase.
Figure B.2 – Crystal unit loss resistance as a function of dissipated power
NOTE The ratio R R is not a reproducible value since the crystal unit curve slightly shifts at different
r 2 r1
measurement cycles.
The negative resistance (and with it the DLD reject level) of the oscillator can be changed by
connecting a positive resistor in series with the oscillator. In this manner, each value between
0 Ω and 200 Ω may be selected. Connecting a quartz crystal unit with a sufficiently low R value
r
between the test clamps, the oscillation will build up starting from the initial noise level
-16 -15
(approximately 10 W to 10 W) to its limiting point for 1 mW as shown in Figure B.5.
During the start-up, the R of the crystal unit is continuously compared with a Calibrated-
rmax
R and the result is detected and transferred into a go/no-go decision.
osc
If the crystal unit under test shows a certain degree of DLD, it is possible that the oscillation
amplitude will not reach the 1 mW limiting point (point B in Figure B.6). In the example given in
Figure B.6, the build-up of the oscillation is terminated at a much lower level of drive (point A).
Normally in such cases, no oscillation is observed and only with very sensitive equipment can
some oscillation be detected.
If a crystal unit reaches the 1 mW level (point B), the LED indicator will light up. This means
that the quartz crystal unit’s resonance resistance did not exceed the DLD reject level during
the start-up.
The advantages of this measurement method are that it is fast, easy to calibrate, inexpensive
and it has a simple set-up. A detailed electrical diagram is shown in Figure B.7. The equipment
is commercially available.
Figure B.3 – Behaviour of the R of a quartz crystal unit
r
Figure B.4 – Block diagram of circuit system
– 18 – IEC 60444-6:2021 © IEC 2021
Figure B.5 – Installed −R in scanned drive level range
osc
Figure B.6 – Drive level behaviour of a quartz crystal unit
if −R = 70 Ω is used as test limit in the Annex B test
osc
Figure B.7 – Principal schematic diagram of the go/no-go test circuit
– 20 – IEC 60444-6:2021 © IEC 2021
Bibliography
IEC 60122-2-1:1991, Quartz crystal units for frequency control and selection – Part 2: Guide to
the use of quartz crystal units for frequency control and selection – Section one: Quartz crystal
units for microprocessor clock supply
Amendment 1:1993
IEC 60444-1, Measurement of quartz crystal unit parameters by zero phase technique in a π-
network – Part 1: Basic method for the measurement of resonance frequency and resonance
resistance of quartz crystal units by zero phase technique in a π-network
___________
– 22 – IEC 60444-6:2021 © IEC 2021
SOMMAIRE
AVANT-PROPOS . 23
INTRODUCTION . 25
1 Domaine d’application. 26
2 Références normatives . 26
3 Termes et définitions . 26
4 Effets de la DNE . 26
4.1 Changements réversibles de la fréquence et de la résistance . 26
4.2 Changements irréversibles de la fréquence et de la résistance . 27
4.3 Causes des effets de la DNE . 27
5 Niveaux d’excitation pour la mesure de la DNE . 27
6 Méthodes d’essai . 29
6.1 Méthode A (méthode de mesure rapide normalisée) . 29
6.1.1 Essai à deux niveaux d’excitation . 29
6.1.2 Essai conformément à la spécification . 29
6.2 Méthode B (méthode de mesure de référence à plusieurs niveaux) . 30
Annexe A (normative) Relation entre le niveau d’excitation électrique et le
déplacement mécanique des résonateurs à quartz . 33
Annexe B (normative) Méthode C: Mesure de la DNE avec un circuit d’oscillation . 36
Bibliographie . 41
Figure 1 – Rapport des résistances maximales tolérables γ pour la dépendance du
niveau d’excitation en fonction des résistances R ou R . 30
12 13
Figure B.1 – Insertion d’un résonateur à quartz dans un oscillateur . 36
Figure B.2 – Résistance de perte d’un résonateur en fonction de la puissance dissipée . 37
Figure B.3 – Comportement de R d’un résonateur à quartz . 38
r
Figure B.4 – Schéma de circuit . 38
−R
Figure B.5 – installée dans une gamme de niveaux d’excitation balayés . 39
osc
Figure B.6 – Comportement du niveau d’excitation d’un résonateur à quartz si −R =
osc
70 Ω est utilisée comme limite de l’essai de l’Annexe B . 39
Figure B.7 – Schéma principal du circuit d’essai tout-ou-rien . 40
COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
MESURE DES PARAMÈTRES DES RÉSONATEURS À QUARTZ –
Partie 6: Mesure de la dépendance du niveau d’excitation (DNE)
AVANT-PROPOS
1) La Commission Electrotechnique Internationale (IEC) est une organisation mondiale de normalisation
composée de l’ensemble des comités électrotechniques nationaux (Comités nationaux de l’IEC). L’IEC
a pour objet de favoriser la coopération internationale pour toutes les questions de normalisation dans
les domaines de l’électricité et de l’électronique. À cet effet, l’IEC – entre autres activités – publie des
Normes internationales, des Spécifications techniques, des Rapports techniques, des Spécifications
accessibles au public (PAS) et des Guides (ci-après dénommés "Publication(s) de l’IEC"). Leur
élaboration est confiée à des comités d’études, aux travaux desquels tout Comité national intéressé par
le sujet traité peut participer. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec l’IEC, participent également aux travaux. L’IEC collabore étroitement
avec l’Organisation Internationale de Normalisation (ISO), selon des conditions fixées par accord entre
les deux organisations.
2) Les décisions ou accords officiels de l’IEC concernant les questions techniques représentent, dans la
mesure du possible, un accord international sur les sujets étudiés, étant donné qu
...
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