IEC 60679-6:2011

IEC 60679-6 ®
Edition 1.0 2011-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Quartz crystal controlled oscillators of assessed quality –
Part 6: Phase jitter measurement method for quartz crystal oscillators and SAW
oscillators – Application guidelines

Oscillateurs pilotés par quartz sous assurance de la qualité –
Partie 6: Méthode de mesure de la gigue de phase pour les oscillateurs à quartz
et les oscillateurs SAW – Lignes directrices pour l'application

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IEC 60679-6 ®
Edition 1.0 2011-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Quartz crystal controlled oscillators of assessed quality –
Part 6: Phase jitter measurement method for quartz crystal oscillators and SAW
oscillators – Application guidelines

Oscillateurs pilotés par quartz sous assurance de la qualité –
Partie 6: Méthode de mesure de la gigue de phase pour les oscillateurs à quartz
et les oscillateurs SAW – Lignes directrices pour l'application

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX S
ICS 31.140 ISBN 978-2-88912-403-9

– 2 – 60679-6 © IEC:2011
CONTENTS
FOREWORD . 4

INTRODUCTION . 6

1 Scope . 8

2 Normative references . 8

3 Terms, definitions and general concepts . 8

3.1 Terms and definitions . 8

3.2 General concepts . 8

3.2.1 Phase jitter . 8
3.2.2 r.m.s jitter . 9
3.2.3 Peak-to-peak jitter . 10
3.2.4 Random jitter . 10
3.2.5 Deterministic jitter . 11
3.2.6 Period (periodic) jitter . 11
3.2.7 Data-dependent jitter . 11
3.2.8 Total jitter . 11
3.3 Points to be considered for measurement . 12
3.3.1 Measurement equipment . 12
3.3.2 Factors of measurement errors . 12
4 Measurement method . 13
4.1 General . 13
4.2 Frequency range and the measurement method . 13
4.3 Method using the phase noise measurement value . 13
4.3.1 Overview . 13
4.3.2 Measurement equipment and system . 13
4.3.3 Measurement item . 13
4.3.4 Range of detuning frequency . 14
4.3.5 Phase noise measurement method . 14
4.4 Measurement method using the specially designed measurement equipment . 14
4.4.1 Overview . 14
4.4.2 Measurement equipment and system . 14
4.4.3 Measurement items . 14
4.4.4 Number of measurements . 14
4.5 Block diagram of the measurement. 14

4.6 Input and output impedance of the measurement system. 15
4.7 Measurement equipment . 15
4.7.1 General . 15
4.7.2 Jitter floor . 15
4.7.3 Frequency range . 15
4.7.4 Output waveform . 15
4.7.5 Output voltage . 16
4.8 Test fixture . 16
4.9 Cable, tools and instruments . 16
5 Measurement and the measurement environment . 16
5.1 Set-up before taking measurements . 16
5.2 Points to be considered and noted at the time of measurement . 16
5.3 Treatment after the measurement . 17

60679-6 © IEC:2011 – 3 –
6 Measurement . 17

6.1 Reference temperature . 17

6.2 Measurement of temperature characteristics . 17

6.3 Measurement under vibration . 17

6.4 Measurement at the time of impact . 17

6.5 Measurement in accelerated ageing . 17

7 Other points to be noted . 17

8 Miscellaneous . 17

Annex A (normative) Calculation method for the amount of phase jitter . 18

Bibliography . 21

Figure 1 – Voltage versus time . 9
Figure 2 – Explanatory diagram of the amount of jitter applied to r.m.s. jitter . 10
Figure 3 – Explanatory diagram of random jitter, deterministic jitter, and total jitter . 11
Figure 4 – Equivalent block diagram . 15
Figure A.1 – Concept diagram of SSB phase noise . 19

– 4 – 60679-6 © IEC:2011
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
QUARTZ CRYSTAL CONTROLLED OSCILLATORS

OF ASSESSED QUALITY –
Part 6: Phase jitter measurement method

for quartz crystal oscillators and SAW oscillators –

Application guidelines
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,
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Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
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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) 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.
International Standard IEC 60679-6 has been prepared by lEC technical committee 49:
Piezoelectric, dielectric and electrostatic devices and associated materials for frequency
control, selection and detection.
This standard cancels and replaces IEC/PAS 60679-6 published in 2008. This first edition
constitutes a technical revision.

60679-6 © IEC:2011 – 5 –
The text of this standard is based on the following documents:

FDIS Report on voting
49/935/FDIS 49/944/RVD
Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts of the IEC 60679 series, published under the general title Quartz crystal
controlled oscillators of assessed quality, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• 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.
– 6 – 60679-6 © IEC:2011
INTRODUCTION
The study of phase jitter measurement methods was conducted in accordance with the

agreement during the IEC TC 49 Berlin international meeting in 2001. At this meeting, the

decision was made that Japan should assume the responsibilities of this study. Then, the

technical committee of the Quartz Crystal Industry Association of Japan (QIAJ) proceeded

with this study. This study was substantially conducted during the years 2002 to 2005 and can

be referred to as the first stage of the study. The second stage is being continued at present.

Phase jitter has become one of the essential measurement items by digitization of electronic

devices. However, theoretically, some ambiguity is still left in the phase jitter. Since no

standard measurement method is proposed, suppliers and customers may be mutually
exposed to a risk which could cause enormous economic losses.
To avoid this risk, this document provides a standard, based on the study results during the
first stage, for each company of QIAJ members to avoid anxiety as to the measurement of the
phase jitter and for the purpose of giving guidance without any mistakes.
In this standard, a recommendation to make r.m.s. jitter a measurement object is presented.
The reason why this recommendation is submitted is because the oscillators resulting in ultra-
low amount of jitter are targeted as the object to be measured.
Oscillators are analogue-type electronic devices. Their sine wave output signals are more
favourable than the signals obtained by electronic systems. Moreover, the output is utilized as
the reference clock of the measurement equipment, leading to a situation in which the amount
of phase jitter is shown to be smaller than the amount of phase jitter of the measurement
equipment. Accordingly, this may give the impression that the measured amount of phase
jitter is not from the oscillators but rather the amount of phase jitter generated by the
measurement equipment, or the measurement system. Therefore, when adopting the amount
of other phase jitters as the measurement items, a recommendation is presented to select
measurement equipment and a measurement system capable of being verified and confirmed
sufficiently, contractually determined between suppliers and customers. Moreover, when the
phase noise method is used, the random jitter values need to be discussed after defining the
jitter frequency bands from start to end of integrating the phase noise.
In case of doubts related to the measurement values, refer to the application of Allan
.
Variance [1]
Frequency stability was compiled into a single work by IEEE in 1966 [2]. Then, the definition
was applied to atomic oscillators, crystal oscillators, as well as electronic systems for
telecommunication, information, audio-visual, and the like.

Conventional crystal oscillators and electronic systems have analogue systems and their
signal waveforms are sine waves. Therefore, the short-term frequency stability as one field of
the frequency stability is measured as the phase noise or Allan Variance. Recently,
digitization of electronic systems is progressing. Under such circumstance, the short-term
frequency stability has been measured as the phase jitter.
On the other hand, the oscillators are analogue-type electronic devices. For the oscillators,
the signals having square waves or waveforms similar thereto are demanded by users to be
easily fit into the electronic systems. Naturally, for the short-term frequency stability, the
measurement as the phase jitter is frequently demanded by users.
For advance application in electronic information and communication technology: (e.g.:
advanced satellite communications, control circuits for electric vehicle (EV) and etc.),
necessity arises for the measurement method for common guidelines of phase jitter. In these
—————————
Numbers in square brackets refer to the Bibliography.

60679-6 © IEC:2011 – 7 –
days, measurement method of phase jitter also becomes more important from the

electromagnetic influence (EMI) point of view.

In that sense, international standardization as IEC 60679-6 of phase jitter measurement

method is significant and timely. The measurement method of phase jitter described in this

document is the newest method by which quantitative measurement was made possible from

the breakthrough of the measurement system technology, in the hope to get attention from not

only a device engineer but also a system engineer and expected to be widely used.

– 8 – 60679-6 © IEC:2011
QUARTZ CRYSTAL CONTROLLED OSCILLATORS

OF ASSESSED QUALITY –
Part 6: Phase jitter measurement method

for quartz crystal oscillators and SAW oscillators –

Application guidelines
1 Scope
This part of the IEC 60679 series applies to the phase jitter measurement of quartz crystal
oscillators and SAW oscillators used for electronic devices and gives guidance for phase jitter
that allows the accurate measurement of r.m.s. jitter.
In the measurement method, phase noise measurement equipment or a phase noise
measurement system is used.
The measuring frequency range is from 10 MHz to1 000 MHz.
This standard applies to quartz crystal oscillators and SAW oscillators used in electronic
devices and modules that have the multiplication or division functions based on these
oscillators. The type of phase jitter applied to these oscillators is the r.m.s. jitter. In the
following text, these oscillators and modules will be referred to as “oscillator(s)” for simplicity.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60679-1:2007, Quartz crystal controlled oscillators of assessed quality – Part 1: Generic
specification
3 Terms, definitions and general concepts
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60679-1:2007 apply.
Units, drawings, codes, and characters are also based on IEC 60679-1.
3.2 General concepts
3.2.1 Phase jitter
The phase jitter of oscillators means an electronic noise of signal waveforms in terms of time.
On the other hand, the phase jitter is described as a jitter in which the frequency of signal
deflection exceeds 10 Hz and as a wander in which the frequency is 10 Hz or less.
It is difficult to observe the wander of oscillators. The wander is a phenomenon which is
confirmed in electronic parts such as optical cables susceptible to expansion and contraction
even by a small amount of temperature changes. Therefore, the wander is generally not
discussed in the oscillators. In this document also, phase jitter is targeted only to the jitter.

60679-6 © IEC:2011 – 9 –
As for signals, an ideal cycle (t) is inversely proportional to a frequency (f). More specifically,

the relation is expressed by Equation (1).

t = (1)
f
Actually, the cycle is varied by receiving various influences. This phenomenon is the phase

jitter and can be confirmed by thickening of edges of waveforms when using oscilloscopes or

the like. Regarding the method for measuring and evaluating such phase jitter, statistical

measurement techniques are utilized as shown is shown in Figure 1. The numerical values in

Figure 1 are treated as a symbol. The position of 0,5 of signal waveform is defined as a

reference point in the vertical axis, and the edges of the reference point are defined to be not
varied. When attention is paid to the edges after one cycle, every time when the signals
repeatedly move on the screen of CRT in the lateral direction, the edges after one cycle are
not reproduced. Then, plurality edges have become to exist. This phenomenon is induced
when repeatedly measuring the signals, and referred to as the phase jitter.

2,0
N
1,5
1,0
0,5
0,0
–0,5
–1,0
Reference point
–1,5
–2,0
0 10 20 30 40 50
Time Time
IEC  527/11
a) Output waveform b) Histogram of the all jitters
Figure 1 – Voltage versus time
This phase jitter is treated as a normal distribution. Then, when analysed, the phase jitter can
be divided into several types of properties. More specifically, the phase jitter is classified in
several types. In this document, the phase jitter is classified in the seven types as described
below. In the following, these properties and the cause systems are made clear.

3.2.2 r.m.s jitter
The r.m.s. jitter is the phase jitter which comes to have the normal distribution shown in
Figure 2. The r.m.s. jitter is a standard deviation obtained on the basis of statistical
treatments and defined as a 1 σ portion
Voltage
– 10 – 60679-6 © IEC:2011
RMS jitter (standard deviation)

Peak-to-peak jitter
IEC  528/11
Figure 2 – Explanatory diagram of the amount of jitter applied to r.m.s. jitter
From statistics, any measurement data is meant to exist in 1 σ at a probability of 68,26 %.
Therefore, when the measurement times are 10 000, approximately 6 826 pieces of the
measurement data are considered to be contained. On the contrary, 31,74 % (3 174 pieces)
of the measurement data is indicated to be outside the plus and minus sides of 1 σ. If the data
outside the definition is considered to be errors, 31,74 % can be considered to be the error
rate.
3.2.3 Peak-to-peak jitter
The peak-to-peak jitter is the phase jitter which comes to have the normal distribution shown
in Figure 2. The amount of phase jitter of one cycle is totalized and statistically treated on the
base point of the reference point of phase jitter shown in Figure 1. In this case, the amount of
phase jitter is assumed to provide the normal distribution.
The difference between the maximum value and the minimum value (namely, change width) is
referred to as the peak-to-peak jitter. Since the jitter values become larger as the
measurement times are increased, the jitter also becomes the total jitter as described later.
This term comes on when negotiating specifications between customers and oscillator makers.
NOTE Since the peak-to-peak jitter or the r.m.s. jitter indicates the amount of phase jitter to the measurement
times thereof, the jitter indicates operating conditions of measurement samples in a short period of time. Moreover,
the jitter has values effective only to an ideal normal distribution (Gaussian distributions), and the effectiveness

can be maintained to be low in cases of non-Gaussian distributions having distorted distributions such as binomial
distributions and chi-square distributions. Accordingly, when applying the peak-to-peak jitter or the r.m.s. jitter, the
measurement times are required to be clearly defined contractually between customers and supplier sides.
3.2.4 Random jitter
The random jitter is shown in Figure 3. The random jitter represents unpredictable phase jitter
components.
The random jitter naturally and inductively occurs as influenced by the characteristics, thermal
noise, etc., originally involved in the measurement equipment per se or oscillators.
Furthermore, random jitter has the characteristics that the distribution width of measurement
values becomes larger (namely, boundless characteristics) as the observation period of time
becomes longer. Therefore, the distribution chart can be considered as an ideal normal
distribution. Moreover, the random jitter is determined as a standard deviation based on the
distribution chart obtained by the measurement of phase jitter. Accordingly, in the case of
oscillators, the random jitter may become the amount of jitter equivalent to the r.m.s. jitter.
Moreover, since the random jitter becomes the amount of jitter of the measurement equipment

60679-6 © IEC:2011 – 11 –
per second, the random jitter is one of the measures for judging applicability to measuring the

phase jitter of oscillators.
Deterministic jitter
Random jitter
Random jitter
Total jitter
IEC  529/11
Figure 3 – Explanatory diagram of random jitter, deterministic jitter, and total jitter
3.2.5 Deterministic jitter
The deterministic jitter occurs by various factors of regularity (circuit designs, electromagnetic
induction, or induced from external environment), and has characteristics inasmuch as the
change width of distribution has a boundary and thus can be expressed by the parts
sandwiched between right and left random jitters. On the other hand, the components forming
the deterministic jitter include the period jitter or periodic jitter and the data-dependent jitter.
3.2.6 Period (periodic) jitter
The period jitter or periodic jitter shows variations of timings of multiple cycles consecutively
provided such as two cycles and three cycles. The period jitter or periodic jitter can be
determined by grasping the relationship with the r.m.s. jitter between the multiple cycles and
each cycle, and thus grasping whether or not periodic irregularities appear. As for the periodic
components of this jitter, such components are considered as an electronic noise caused by
the power supply and cross-talk from electronic parts around oscillators to be measured, and
further from cores in the vicinity in the case of IC.
If the Fast Fourier Transform (FFT) can be executed, the frequency as the cause clearly
appears as a spectrum. Although this jitter is naturally required to be considered for the
oscillators, it is difficult to detect the jitter by using measurement equipment in general.
3.2.7 Data-dependent jitter
The data-dependent jitter is considered to be the jitter components due to duty cycle
distortion and inter symbol interference, and is negligible for oscillators.
3.2.8 Total jitter
The total jitter is defined as the jitter obtained by totalizing all of the jitters.

– 12 – 60679-6 © IEC:2011
3.3 Points to be considered for measurement

3.3.1 Measurement equipment
For the oscillators, requests of infinite variety are provided by customers. The output
waveforms are not limited to square waves. The demands for output voltage as small as not

applicable to the measurement equipment may also be provided.

Since the oscillators have an ultra-low noise, such a case may be experienced that the

amount of jitter of the measurement equipment per se is detected. Therefore, for the amount

of jitter of the measurement equipment per se, the measurement equipment shall have the

jitter floor smaller by one digit as compared with the amount of jitter of assumed oscillators.

Moreover, the frequency range and the output waveforms are requested to be applicable not
only to square waves but also to sine waves.
Since measurement equipment in general, are provided with the specification of a degree
applicable to digital electronic systems, a sufficient study is required for adapting the
measurement equipment for oscillator purposes.
a) In case of digital oscilloscopes, no appropriate measurement equipment for such oscillator
purpose is found.
b) When applying digital oscilloscopes to the phase jitter measurement, it is recommended to
select the measurement equipment and the measurement system capable of being
sufficiently verified and confirmed, and to be determined by contract between suppliers
and customers.
c) When applying time interval based analysers to the phase jitter measurements, the
following shortcomings are observed; compared to oscillators, the random jitter of jitter
floor is equivalent, or larger; the application of sine waves is difficult; the low frequency
cannot be applied to the range of such oscillators, and the output voltage is low so that an
amplifier is required. Therefore, selecting the time interval based analysers requires
careful consideration.
d) The phase jitter may be calculated from phase noise measurement values by using the
phase noise measurement equipment or measurement system. In this case, the detuned
frequency shall be determined by contract between suppliers and customers. When the
detuned frequency does not remain in the range of the phase noise measurement
equipment or the measurement system, in particular, when the upper limit of the detuned
frequency becomes a floor level, care shall be taken not to create misunderstanding
between customers and suppliers, by defining that the voltage of floor level is exactly
according to the contract established between them.
Within the range investigated during the first stage of the study, no devices satisfying the
requirements were found among sampling oscilloscopes and specially designed measurement
equipment. However, since information is obtained that a part of specially designed

measurement equipment satisfying the requirements has been put on the market, the
specially designed measurement equipment falls within the scope of this standard.
3.3.2 Factors of measurement errors
With regard to oscillators, the factors contributing to phase jitter measurement errors are the
following:
a) Power supply
The power supply is required for driving the oscillators. If unstable power supply is used,
the unstable power supply is observed as converted into jitter. Therefore the use of power
supply having a sufficiently low noise is desirable. Since losses occur on the wiring cable
between power supply terminals and oscillators or amplifiers, and since contact resistance
is produced, the amount of phase jitter may be increased from this part.
b) Test fixer and load
60679-6 © IEC:2011 – 13 –
The load is formed of resistors and fixed capacitors. Since the resistors exist, generation

of electronic noise cannot be avoided. The possibility of playing a role in collecting the

electronic noise as an antenna may be exemplified.

c) Amplifier (when an amplifier at the time of measurement is used)

The amplifier is formed of electronic parts including active elements and resistors.
Therefore, generation of electronic noise cannot be avoided.

d) Cable
The cable including losses therein and therefore is a source of / generating electronic

noise. Since the reflectance changes as the impedance changes in function of the length

caused by temperature characteristics, the change may be misread as the wander. An

electronic noise due to contact change of connectors may occur. The possibility of playing
the role of collecting the electronic noise as an antenna may be exemplified.
e) Input-output impedance of measurement system
The load impedance of oscillators widely ranges from 5 Ω to 100 MΩ. The parts used for
the load impedance include the following three types:
1) capacitor only;
2) resistance element only;
3) combined use of a capacitor and a resistance element.
In 1) only the capacitor phase jitter measurement values can be neglected. In 2) and in 3)
attention is needed because the phase jitter measurement values cannot be neglected by
the thermal noise from the resistance element.
f) Measurement of phase jitter for frequencies exceeding 1 GHz
In general, the waveforms of signals (including demodulated signals) exceeding 1 GHz are
modified sine waves. Therefore, attention is needed because the amount of phase jitter,
which suppliers and customers intended, may be difficult to obtain by sampling
oscilloscopes or specially designed measurement equipment.
4 Measurement method
4.1 General
The measurement method applied to oscillators is based on the following.
4.2 Frequency range and the measurement method
The measurement range shall be 10 MHz to 1 000 MHz. The phase noise measurement
equipment (system) or the specially designed phase jitter measurement equipment shall be
used as measurement method.
4.3 Method using the phase noise measurement value
4.3.1 Overview
The recommended method for measuring phase jitter using phase noise measurements is as
given in 4.3.2 to 4.3.4 below.
4.3.2 Measurement equipment and system
The measurement equipment and system shall be the phase noise measurement equipment
or the phase noise measurement system.
4.3.3 Measurement item
The measurement item shall be the r.m.s jitter.

– 14 – 60679-6 © IEC:2011
NOTE Only random jitter. No period jitter.

4.3.4 Range of detuning frequency

The range of detuning frequency should be determined through a prearrangement and

contract between a customer and a supplier. The formula to calculate phase jitter from phase

noise is described in Annex A.

4.3.5 Phase noise measurement method

The range of detuned frequency shall be determined by contract between customers and

suppliers after discussion. The formula for calculating the r.m.s. jitter from phase noise is

based on the calculation method for the amount of phase jitter shown in Annex A.
An orthogonal phase detection method (also referred to as orthogonal comparison method or
PLL method), or the measurement equipment having built-in electronic circuits for cancelling a
noise in the measurement system (for example, circuits adopting a cross-correlation method)
shall be used as phase noise measurement methods.
4.4 Measurement method using the specially designed measurement equipment
4.4.1 Overview
The requirements for the method using the specially designed measurement equipment are
based on the following.
4.4.2 Measurement equipment and system
The measurement equipment and system shall be the specially designed SONET/SDH
measurement equipment using a time interval analyser.
4.4.3 Measurement items
The measurement items shall be the r.m.s jitter and the period (periodic) jitter.
4.4.4 Number of measurements
The number of measurements shall be determined by contract between customers and
suppliers after discussion. The target number of measurements shall be 20 000 times or more.
NOTE Attention is needed because this device may not meet the requirements of oscillators for the following
reasons:
a) The measurable range of the measurement equipment may not meet the frequency of the oscillators to be
measured.
b) The output voltage of the oscillators is lower as compared with this device. For this reason, an amplifier is
required, and the necessity of evaluating the phase jitter of the amplifier arises.
c) The realization of square waves, such as CMOS, LVDS, and LVPECL, is difficult because harmonics
components decrease in the frequency bands exceeding 300 MHz. For this reason, the signal waveforms
become sine waves, clipped-sine waves and the like. It is difficult to analyse them by the specially
designed SONET/SDH measurement equipment, and thus a decrease in measurement accuracy is
possible.
4.5 Block diagram of the measurement
A representative block diagram is shown in Figure 4. A practical block diagram is utilized as
modified forms of Figure 4.
60679-6 © IEC:2011 – 15 –
Measurement
Test fixture
equipment load
Sample
Power supply
oscillator
IEC  530/11
Figure 4 – Equivalent block diagram
4.6 Input and output impedance of the measurement system
The load impedance of oscillators widely ranges from 5 Ω to 100 MΩ. The parts to be applied
are the types shown below. However, since numerous demands are made by customers, the
values of this load impedance are infinite.
a) capacitor only;
b) resistor only;
c) both, capacitor and resistor;
d) compliment output with bias.
Here, since the measurement system is unified into 50 Ω, the input-output impedance of
measurement systems shall be 50 Ω. For this reason, the load impedance of oscillators shall
also be 50 Ω.
The changes of the oscillation output voltage depends on the load impedance of oscillators.
For this reason, the thermal noise of load circuits also changes.
As a result, since the amount of phase jitter changes, a recommendation is presented to
suppliers and customers, when adopting any load impedance other than 50 Ω, to conduct a
detailed study and examination and to determine the impedance contractually.
4.7 Measurement equipment
4.7.1 General
The requirements for the measurement equipment are described in the following subclauses.
There is no necessity of adhering to these requirements. However, it is important to adopt

measurement equipment satisfying the requirements of oscillators.
4.7.2 Jitter floor
The jitter floor shall take values of 0,05 ps or less as the random jitter or values smaller by
one digit as compared with the phase jitter demanded for the oscillators.
4.7.3 Frequency range
The frequency range shall be 10 MHz to 1 000 MHz. Several items of measurement
equipment may be used according to each frequency band.
4.7.4 Output waveform
The output waveforms shall be CMOS, LVDS, LVPECL, clipped-sine waves, sine waves, etc.

– 16 – 60679-6 © IEC:2011
NOTE CMOS, LVDS, and LVPECL originally refer to the type of devices and not to a waveform per se. However,

they are also used as the terms for waveforms and are, therefore, described as the type of output waveforms in
this document.
4.7.5 Output voltage
The output voltage shall be 350 mV or more.

4.8 Test fixture
The requirements for measurement implements are shown below:

a) Connection between oscillators to be measured and measurement implements

The application of sockets, connectors, screws, clips, and the like may be allowed. In
addition, the oscillators to be measured and the measurement implements shall be
ensured to be mechanically and electrically connectable.
b) Compatibilization of oscillators to be measured and measurement implements
The osci
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