Iec 60195 2016

Method of measurement of cur ent noise generated in fixed resistors Méthode pour la mesure du bruit produit en charge par les résistances fixes... Method of measurement of cur ent noise

Method of measurement of cur ent noise generated in fixed resistors

Méthode pour la mesure du bruit produit en charge par les résistances fixes

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Method of measurement of cur ent noise generated in fixed resistors

Méthode pour la mesure du bruit produit en charge par les résistances fixes

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CONTENTS

FOREWORD 4

1 Sco e 6

2 Normative referen es

6 3 Terms an definition 6

4 Method of me s rement 7

4.1 Noise b sic 7

4.1.1 Noise 7

4.1.2 Thermal noise 8

4.1.3 Cur ent noise 8

4.2 Me s rement prin iple 9

4.3 Me s rement s stem 10 4.3.1 Pro osal of a s ita le me s rin s stem 10 4.3.2 Alternative me s rin s stems 1

4.4 Me s rement s stem req irements 1

4.4.1 Input circ it 1

4.4.2 Isolation resistor R M 12 4.4.3 DC voltage source 12 4.4.4 DC electronic voltmeter 12 4.4 5 Cal bration resistor R Cal 1

2 4.4.6 Cal bration source 13 4.4.7 Determination of the calbration voltage 13 4.4.8 AC b n -p s ampl fier 15 4.4 9 AC r.m.s meter 1

6 4.4.10 Test fixture 16 4.5 Verification of the me s rin s stem 17 4.5.1 Performan e c eck by me s rement of in trument an thermal noise 17 4.5.2 Performan e c eck by comp rison of re e ted me s rements 17 5 Me s rement proced re 18 5.1 Ambient con ition 18 5.2 Pre aration of sp cimen 18 5.3 Proced re 18 5.3.1 General 18 5.3.2 Cal bration 18 5.3.3 Me s rement of s stem noise S 18 5.3.4 Me s rement of total noise T 19 5.4 Precaution 2

6 Evaluation of me s rement res lts 2

6.1 Term for the contribution of s stem noise 2

6.2 Determination of the c r ent noise in ex A 1 2

6.3 Determination of the c r ent noise voltage ratio CNR U 25 6.4 Ac urac 2

6.5 Req irements 2

7 Information to b given in the relevant comp nent sp cification 2

An ex A (informative) L ter s mb ls an a breviation 2

A.1 L ter s mb ls 27

A.2 Ab reviation 2

An ex X (informative) Cros -referen e for referen es to the prior revision of this

stan ard 2

Bibl ogra h 2

Fig re 1 – Block s hematic of a s ita le me s rin s stem 11

Fig re 2 – Typical tran fer fu ction of the b n -p s ampl fier 16

Fig re 3 – Contribution of s stem noise, f(T – S) 2

Ta le 1 – Permis ible l mits of s stem noise 1

7

Ta le 2 – Recommen ed o eratin con ition ( of 2) 2

Ta le 3 – Numeric values of the contribution of s stem noise, f(T – S) 2

Ta le X.1 – Cros referen e for referen es to the 1

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International Stan ard IEC 6 19 has b en pre ared by IEC tec nical commite 4 :

Ca acitors an resistors for electronic eq ipment

This secon edition can els an re laces the first edition publ s ed in 19 5 an con titutes a

tec nical revision

This edition in lu es the fol owin sig ificant tec nical c an es with resp ct to the previou

• complete editorial revision.

The text of this stan ard is b sed on the fol owin doc ments:

Ful information on the votin for the a proval of this stan ard can b fou d in the re ort on

votin in icated in the a ove ta le

This publcation has b en drafed in ac ordan e with the ISO/IEC Directives, Part 2

The commit e has decided that the contents of this publ cation wi remain u c an ed u ti

the sta i ty date in icated on the IEC we site u der "htp:/we store.iec.c " in the data

related to the sp cific publ cation At this date, the publ cation wi b

METHOD OF MEASUREMENT OF CURRENT

This International Stan ard sp cifies a method of me s rement an as ociated test

con ition to as es the "noisines ", or mag itu e of c r ent noise, generated in fixed

resistors of an given typ The method a pl es to al clas es of fixed resistors The aim is to

provide comp ra le res lts for the determination of the s ita i ty of resistors for u e in

electronic circ its havin critical noise req irements

The c r ent noise in resistive materials reflects the gran lar stru ture of the resistive material

For some resistor tec nologies uti zin homogenou layers it is regarded as providin an

in ication of defects, whic are con idered as a ro t cau e for a normal agein of the

comp nent u der the influen e of temp rature an time

The method des rib d in this International Stan ard is not a general sp cification req irement

an therefore is a pl ed if pres rib d by a relevant comp nent sp cification, or, if agre d

b twe n a c stomer an a man facturer

2 Normativ referenc s

The folowin doc ments, in whole or in p rt, are normatively referen ed in this doc ment an

are in isp n a le for its a pl cation For dated referen es, only the edition cited a pl es For

u dated referen es, the latest edition of the referen ed doc ment (in lu in an

combination of al ran om flu tuation of c r ent flow in a resistor whic are not atributed to

thermal agitation of the c arge car iers ( hermal noise) an whic de en on the a pl ed

logarithmic in ex of the ratio of the o en circ it r.m.s c r ent noise voltage in a freq en y

decade, in µV, over the d.c voltage a pl ed u der test, in V, u ed to expres the “noisines ”

of an in ivid al resistor

Note 1 to e try: Th c re tn ise in e is e pres e in dB Th ratio b twe n µV a d V is n t c nsid re in this

in e , le din to its v lu b in 12 dB les th n th math matic l c re t n ise in e A

1

′ This pra tic l in e

folows th history of prior re isio s of this meth d

logarithmic in ex of the ratio of the o en circ it r.m.s c r ent noise voltage in a freq en y

decade over the d.c voltage a pl ed u der test, esta l s ed in con istent u its an their

multiples

Note 1 to e try: Th math matic l c re tn ise in e is e pres e in dB This in e h s b e intro u e for th

math matic l d riv tio of th c nsid re p rameters

3.4

c r ent noise voltage ratio

CN R

U

ratio of the o en circ it r.m.s c r ent noise voltage in a freq en y decade over the d.c

voltage a pled u der test, esta l s ed in µV/V, u ed to expres the “noisines ” of an

in ivid al resistor

3.5

fl ck r noise

pink noise

ran om flu tuation present in most electronic devices an typical y related to internal

pro erties of the resp ctive device, whic de en s on direct c r ent an has a p wer sp ctral

den ity in ersely pro ortional to the freq en y

3.6

noise

ran om flu tuation in an electrical sig al havin in tantane u ampl tu e values whic , d e to

their distribution in a ran om man er, can only b predicted in terms of pro a i ty statements

3.7

s ot noise

ran om flu tuation in electric c r ent d e to the flowin c r ent con istin of dis rete c arges,

whic is in e en ent of temp rature an has ne rly con tant p wer sp ctral den ity

throu hout the freq en y sp ctrum

3.8

thermal noise

ran om flu tuation generated by the thermal agitation of the c arge car iers (u ualy the

electron ) in ide an electrical con u tor at eq i brium, whic is in e en ent of an a pl ed

voltage an has ne rly con tant p wer sp ctral den ity throu hout the freq en y sp ctrum

Note 1 to e try: Th rmal n ise is alsorefere to as Jo nso n ise or as Ny uist n ise

values

Noise voltage is a statistical y in e en ent ran om varia le, where for most kin s of noise the

freq en y distribution of ampl tu es fol ows a Gau sian distribution c rve Therefore noise

voltage can ot b predicted ex e t in terms of pro a i ty statements

Us al y the c aracteristic of prin ip l interest is not the in tantane u ampl tu e value but the

"time-averaged" value

The me s rement of ampl tu e commonly u ed an ado ted for this International Stan ard is

the efective (r.m.s.) voltage E

n

o served in a p rtic lar freq en y p s -b n

4.1.2 Thermal noise

The thermal noise of a resistor is a flu tuatin voltage cau ed by the ran om motion of

thermaly agitated c arges, whic is present in al resistors The ro t me n-s uare value of

the flu tuatin voltage a p arin at the o en-circ it terminals of a resistor, whic would b

in icated by the me s rin s stem, may b calc lated u in Ny uist’s eq ation:

fRTke

2

thth

∆f is the b n width of the ef ective b n -p s fi ter of the me s rin s stem

The presen e of thermal noise can ot b ig ored b cau e the thermal noise of the resistor

u der test is freq ently a major source of interferen e in the me s rement

4.1.3 Cur ent noise

The presen e of direct c r ent in a fixed resistor cau es an in re se in the o served total

noise a ove the level at ributed to thermal noise Regardles of its originatin nature, this

ex es noise is refer ed to as c r ent noise

2

c2

th2

is the efective voltage of the c r ent noise in a given b n width

Hen e, the c r ent noise is the ge metric dif eren e b twe n the total noise an the thermal

noise

2

th2

t2

c

EE

fe

2

2

~)(

where

e(f) is the momentary voltage of the c r ent noise as a fu ction of freq en y;

I is the d.c c r ent p s in throu h the resistor;

f is the freq en y for whic the c r ent noise voltage is con idered.

The ef ective c r ent noise voltage for a given b n width is calc lated by integratin the

c r ent noise voltage over the freq en y b n

22

I

f

fI

ffeE

If the me n-s uare voltage is in ersely pro ortional to freq en y, then ideal rectan ular p s

-b n s havin eq al ratios of up er to lower b n -p s lmits tran mit eq al amou ts of noise

voltage from a given noise source

A resistor ex ibitin c r ent noise may b re resented as a noise source havin a z

ero-imp dan e c r ent noise voltage generator con ected in series with an in e en ent thermal

-noise voltage generator an with a noise- re resistor

It is recommen ed, however, to a ply a harmonized set of o eratin con ition in order to

en ure the most comp ra le me s rements for al resistors

Ta le 2 gives a set of o eratin con ition recommen ed for the testin of resistors with

resistan es in the ran e of 10 Ω to 2 MΩ The values given therein also avoid overlo din

the sp cimen an the input circ it

The freq en y de en en e of noise voltages req ires the pres ription of a freq en y p s

-b n to b u ed in this me s rement, whic is an ide l rectan ular p s -b n of one

freq en y decade, ge metrical y centered at 1 0 0 Hz

The me s rement res lts in the mathematical c r ent noise in ex in a freq en y decade, A

1

′

as fol ows:

dBlg

2

T1

The typical mag itu e of the c r ent noise voltage b in in the microvolt ran e rather than in

a volt ran e is reflected in the prevalent c r ent noise in ex in a freq en y decade, A

1,

dBlg

2

T1

is the d.c voltage a pl ed to the resistor u der test, given in V

The ratio b twe n µV an V, whic res lts in an ofset of 12 dB, is neglected in the

traditional definition of the c r ent noise in ex A

1, hen e the folowin relation hip a pl es:

dB

12

11

−

′

= A

Sin e the c r ent noise p wer sp ctrum a proximates to a 1/ffreq en y c aracteristic, the

in ex an the ratio provides an estimate of c r ent noise in an freq en y decade

4.3 Me s rement s stem

4.3.1 Proposal of a s ita le me s rin s stem

Fig re 1 s ows a block s hematic of a s ita le me s rin s stem

A thre -p sition switc may b u ed to ac es an of the thre modes of o eration normaly

fol owed in the me s rement proced re:

• cal bration;

• me s rement of s stem noise;

• me s rement of total noise

The input circ it con ists of the resistor u der test R

T, the isolation resistor R

M

an the

cal bration resistor R

Cal, where the isolation resistor R

M

is req ired to red ce the s u tin

ef ect of the d.c s p ly s stem on the noise generated in the resistor u der test

P DC v lta e so rc

G Calbratio so rc , f= 1 kHz

Positio 2: System n ise

Positio 3: Total n ise

The pro osal of a me s rin s stem in 4.3.1 inten s to u ify the test an me s rement

proced res u ed for the as es ment of the c r ent noise generated in fixed resistors This

s stem, however, is not neces ari y the only s stem whic can b u ed, ex e t when

sp cifical y desig ated as refere or referen e method

The provider an u er of an alternative me s rin s stem s al demon trate that s c

s stem wi give res lts eq ivalent to those o tained by the pro osed s stem

4.4 Me s rement s stem req irements

4.4.1 Input circ it

The input imp dan e of the me s rement s stem is influen ed by the imp dan e of the d.c

electronic voltmeter, whic is in p ral el with the isolation resistor R

The input imp dan e of the d.c electronic voltmeter s al me t the impedan e req irement

given in 4.4.4 in order to avoid an detrimental influen e on the me s rement

resistan e values of the sp cimen, whic may b switc ed into the circ it as req ired The

isolation resistor s al b c r ent noise- re ( or example, go d q al ty wirewou d resistors)

Eac isolation resistor s al have a rated dis ip tion of at le st 1 W an the resistan e

toleran e s al b ±1 %

At le st four isolation resistors R

Mare req ired if the ran e of sp cimen resistan e exten s

from 10 Ω to 2 MΩ Examples for s ita le values of R

Mare 1 kΩ; 10 kΩ; 10 kΩ an 1 MΩ

These values are u ed for esta l s in the test con ition in Ta le 2

4.4.3 DC voltage source

The d.c voltage source s al b ca a le of s p lyin a s ita le ran e of voltages, whic

de en s on the sp cimen resistan e R

T, on the req ired test voltage U

T, an on the isolation

There may b some h m an noise interferen e introd ced by the d.c voltage source when it

drives a c r ent throu h the resistor u der test The influen e of this on the o served noise

in ex s al not ex e d 0,5 dB, when the con ected test resistor is known not to generate an

c r ent noise itself (e.g a go d q alty wirewou d or metal foi resistor)

4.4.4 DC electronic voltmeter

The voltmeter u ed for me s rin the d.c test voltage U

T

s al have a con tant imp dan e of

at le st 4 MΩ in the freq en y ran e from 0 Hz to 1 6 0 Hz

The meter, in conju ction with a ste at en ator, s al b cap ble of in icatin the req ired

d.c test voltages with an ac urac of ± % The time con tant s al b les than 0,5 s

The meter s al s p ort the re din of the d.c test voltage U

lg2

The cal bration resistor s al b selected for the lowest p s ible generation of c r ent noise

(e.g a go d q al ty wirewou d or metal foi resistor)

4.4.6 Cal bration source

The cal bration source s al b a sta le sine-wave generator with a fixed freq en y within the

ran e of 9 0 Hz to 1 0 0 Hz Its output s al s p ly a voltage acros the cal bration resistor

R

Cal

, whic is adju ta le within a ran e from 0,6 mV to 0,7 mV, where the actual req ired

cal bration voltage is determined in 4.4.7 The sta i ty of the adju ted calbration voltage s al

b b ter than ± %

The cal bration source is con ected to the me s rin s stem only in cal bration mode

4.4.7 Determination of the cal bration voltage

The cal bration voltage U

Cal

is determined to prod ce a noise meter re din eq al to that

prod ced by a c r ent noise voltage havin an r.m.s value of 1 mV in a freq en y decade

In 4.1.3 it has b en s own that the ef ective c r ent noise voltage de en s of the d.c c r ent

c

ln

~

ff

IE

where

E

c

is the ef ective voltage of the c r ent noise in a given b n width;

I is the d.c c r ent p s in throu h the resistor;

10 f

For the con idered referen e con ition with

mV1

c

=E

the a ove relation hip is

(1 mV) ~ ln(10)

22

I

where

I is the d.c c r ent p s in throu h the resistor

For this method an ide l b n -p s fi ter of 1 kHz b n width, ge metricaly centered at 1 kHz

Cal

ln

~

ff

IU

where

U

Cal

is the cal bration voltage req ired to ac ieve a 1 mV p r freq en y decade re din ;

I is the d.c c r ent p s in throu h the resistor;

)mV1(

12

22

U

an finaly in the determination of the calbration voltage as

( )

mV1

10lnln

12

ln

ff

For the pres rib d ide l b n -p s fi ter of 1 kHz b n width, ge metrical y centered at 1 kHz,

the calc lation res lts in A

i

= 0,9 2

Hen e, for this case the req ired calbration voltage is

mV0,6 6

mV

6 9,0

,0

Cal

=

×

=U

For an p rtic lar non-ide l b n -p s fiter, value A can b computed as folows

a) The voltage gain is me s red throu hout the p s -b n of the s stem vers s freq en y,

where the voltage gain is the ratio of the output voltage, as in icated by the output meter,

to the input voltage, a pl ed acros the terminals of the cal bration resistor

b) The p wer gain is calc lated by s uarin of the voltage gain for e c freq en y

c) Eac p wer gain value is divided by its resp ctive freq en y an ploted again t

freq en y in a l ne r diagram

d) The are u der the res ltin c rve is planimetrical y me s red to give the value A for the

resp ctive non-ide l b n -p s fi ter, where the ac urac of this determination s al b

within ± ,5 % of the res lt

Where there is the res lt of a n merical simulation avai a le of the gain over freq en y of a

desig ed b n -p s fi ter, with the gain typical y given in dB, the proced re des rib d a ove

can b exec ted n merical y, e.g u in a calc lation spre d he t

NOT Th n meric l d termin tio of th are u d r th p s -b n sh wn in Fig re 2 results in a v lu

A = 0,9 9, whic le ds to a re uire c lbratio v lta e U

The ampl fier gain s al b s f icient to me s re circ it noise with the input terminals s orted

an with the adju ta le gain control, des rib d b low, set ne r its minimum gain p sition

In a verification with R

M

≥ 10 kΩ an no d.c c r ent present, the circ it noise s al b no

gre ter than that eq ivalent to the thermal noise of a 6,2 kΩ resistor Therefore, the in re se

in the output re din when the s ort is re laced by a resistor of 6,2 kΩ with a relative

toleran e of ± % s al b at le st 3 dB with the gain control setin k pt u c an ed

The ampl fier s al b ca a le of me s rin input sig als up to 6 0 µV This sig al ampl tu e

gives a s ale re din of a proximately 6 dB when the s stem is cal brated

A contin ou ly adju ta le gain control s al b provided for maintainin a fixed overal s stem

gain whic would otherwise vary with input con ition l sted in Ta le 2 The neces ary gain

control ran e is a proximately 3 dB

The p s -b n s al b flat, s al have a fixed half p wer p s -b n of a proximately

1 0 0 Hz within the lmits ± 0 Hz an s al b ge metricaly centered at 1 0 0 Hz ± 5 Hz

Rip le in the flat to of the p s -b n s al not ex e d ± ,2 dB Fig re 2 s ows the tran fer

fu ction of a b n -p s me tin these req irements

Fig re 2 – Typical transfer function of the b nd-pas ampl fier

These req irements s al b satisfied for al me s rement con ition l sted in Ta le 2 Neither

the are u der the p s -b n , A, as determined in 4.4.7, nor the half p wer p s -b n s al

vary with resp ct to me s rement con ition by more than ± % for an recommen ed

me s rement con ition Compl an e at 10 Ω an at 2 MΩ is con idered s ficient

The a.c ampl fier s al resp n to noise sig als without introd cin a sig ificant er or d e to

cl p in This req ires the d namic ran e to exten at le st 10 dB b yon the in icated a.c

r.m.s value

4.4.9 AC r.m.s meter

The a.c me s rin s stem s al b calbrated in dB from − 0 dB to at le st + 0 dB with 0 dB

b in 1 µV in a freq en y decade The ac urac of the a.c r.m.s meter s al b ± ,4 dB The

time con tant s al b in the ran e of 0,8 s to 1,5 s

4.4.10 Test fixture

The test fixture for the resistor u der test, R

T, s al b ca a le of providin a safe electrical

con ection an s f icient s ieldin from an external field

The le d- o-le d an le d- o-grou d ca acitan es of the resistor u der test in its test fixture

an of the le d to the input of the b n -p s ampl fier s al b minimized, e.g by the u e of

s ort le d , adeq ate sp cin an careful mou tin

Go d s ieldin practice s al b ado ted in the con tru tion of the me s rement s stem The

input circ it o erates at extremely low sig al levels, whic ma es it neces ary that al p rts

an le d in the input circ it b very wel s ielded Comp nents car yin large sig als s ould

not b located ne r the input circ it

IEC Fre u n y (Hz)

4.5 Verification of the me s rin s stem

4.5.1 Performan e c eck by me s rement of in trument and thermal noise

It is recommen ed to verify the p rforman e of the me s rement s stem by c eckin the

level of s stem noise, in lu in thermal noise, without in olvin an sp cimen

For a me s rement s stem as pro osed in 4.3, the fol owin proced re s ould b a pl ed:

a) turn the fu ction switc to “cal bration” an s ort circ it the terminals for the sp cimen R

T

;

b) adju t the gain of the b n -p s ampl fier to the cal brate l ne on the a.c r.m.s meter;

NOT Th c lbratio ln ty ic ly is a ln c ntre o th a.c r.m.s meter sc le With th me surin system

set in c lbratio mo e th meter is c n e te with ut a ate u tor n twork

c) turn the fu ction switc to “s stem noise” an re d the noise in ex S

M

There may b diferent p rforman e c eck proced res an p rmis ible l mits pres rib d for

practical re l zation of the me s rement s stem pro osed in 4.3.1, or for alternative

me s rin s stems as s g ested in 4.3.2

4.5.2 Performan e c eck by comp rison of re e ted me s rements

It is recommen ed to verify the p rforman e of the me s rement s stem by c eckin the

c r ent noise of sp cific resistor sp cimen af er re e ted me s rements

A practical me n of monitorin the sta i ty of the me s rement s stem is to k e a record of

the me s rements made on a set of sp cific control resistors, where it is desira le for the set

of control resistors to con ist of dif erent typ s of resistors an to re resent a large ran e of

resistan e an c r ent noise values

Plotin the data again t time in the form of a control c art for e c sp cimen is s g ested as

a simple an ef ective me n for detectin an ir eg larity within the me s rement s stem

5 Measurement proc dure

5.1 Ambient con itions

The me s rement s al prefera ly b made u der stan ard atmo here for refere

me s rements an test as given in IEC 6 0 8-1:2 13, 4.2

– Relative h midity: 4 % to 5 %

A relevant sp cification may pres rib other ambient con ition for this me s rement

NOT Th g n raly a ple sta d rd atmosp eric c n itio s for testin with th ir wid r p rmis ible temp rature

ra g are n t re omme d ble for this test d e to th influ n e of temp rature o th me sureme t, e.g b me ns

b) me s rement of s stem noise;

c) simultane u me s rement of total noise an of the d.c voltage acros the sp cimen

Con idera le savin of time can b ac ieved when groups of simi ar resistors are to b

me s red by ta in ad antage of the sta i ty of the p rtic lar test eq ipment The intervals

de en ent on the sta i ty of the eq ipment an on the ac urac req ired

5.3.2 Cal bration

The resistor to b tested, R

T, s al b in erted into the test fixture, an the a pro riate

isolation resistor R

M

s al b switc ed into the circ it The al ocation given in Ta le 2 s al

a ply, u les other provision are made by the relevant sp cification

With the me s rin s stem set into config ration for cal bration, the isolation resistor R

M

is

con ected to grou d in te d of to the d.c voltage source, an the 1 0 0 Hz cal bration

voltage is con ected to the cal bration resistor R

Cal

The gain control of the b n -p s ampl fier s al b adju ted so that the noise voltage meter

in icates + 0 dB, or its eq ivalent 1 mV, in a freq en y decade

With the me s rin s stem config red to me s re s stem noise, the isolation resistor R

M

is

con ected to grou d in te d of to the d.c voltage source, an the cal bration resistor R

Calis

dis on ected from the cal bration voltage

The s stem noise in ex S is re d on the noise voltage meter afer a minimum delay of 5 s,

al owin the meter to re c a re resentative me n value

s al b set ac ordin to the pres ription given in Ta le 2, u les other

provision are made by the relevant sp cification, e.g in con ideration of the dis ip tion

ratin of a p rtic lar style of resistors For values of R

T

not contained in Ta le 2, it is s ita le

to a ply the p rameters for the next lower given value

The d.c test voltage in ex D

, is re d on the d.c voltmeter, an the total noise in ex

T

is re d

on the noise voltage meter afer a minimum delay of 5 s, al owin the meter to re c a

re resentative me n value

Th v lu s for this ta le are esta lsh d u d r th folowin prere uisites:

– Th v lta e tob pro id d b th intern l d.c v lta e so rc sh l n t e c e 4 0 V

– Th v lta e U

T

at th resistor sp cime sh l n t e c e 2 0 V

– Th dis ip tio o th isolatio resistor R

5.4 Precautions

Re sona le precaution s c as are commonly as ociated with sen itive me s rements

s ould b fol owed when o eratin the test set The o eratin location s ould b fre of

stron mag etic an electric field an of sources of electro-magnetic radiation Ordinariy, it

ne d not b o erated in a s re ned ro m The location s ould b fre from stron mec anical

vibration an from sources of lou sou d These precaution are mentioned to serve as a

g ide in selectin s ita le location The s ita i ty of a location can b determined by

comp rin test set p rforman e in the selected location with that o tained in a "q iet"

location Us al y, sources of interferen e are re di y identifia le

6 Evaluation of meas rement res lts

6.1 Term for the contribution of s stem noise

The total noise voltage is the ge metric s m of the s stem noise voltage an the c r ent

noise voltage of the resistor u der test

2

c2

s2

t

EE

is the efective c r ent noise voltage in a given b n width

NOT For pra tic l re so s, th se n isev lta es are g n raly giv n in µV

This eq ation can b re r an ed for E

c

2

s2

t2

c

EE

Eac noise voltage can b re laced by a term b sed on its logarithmic in ex,

dB

µV1

lg2

lg2

C is the logarithmic in ex of the c r ent noise voltage, s aled at 0 dB = 1 µV;

T is the logarithmic in ex of the total noise voltage, s aled at 0 dB = 1 µV;

S is the logarithmic in ex of the s stem noise voltage, s aled at 0 dB = 1 µV

dB22

dB22

dB2

=

ST

TC

whic p rmits to isolate a term for the contribution of s stem noise in relation hip to the total

10)(

STf

Figure 3 – Contribution of s stem noise, f(T – S)

Fig re 3 s ows the res lt of f(T − S) plot ed over (T − S) an i u trates the sp cial

con ideration dis u sed b low

– The ac urac of the determination of the c r ent noise deteriorates if the total noise

a pro c es the s stem noise, whic is the case for (T – S) < 1,0 dB For s c a case the

re ortin of se min ly ac urate values for the c r ent noise in ex A

1.is no lon er

a pro riate

– The contribution of the s stem noise may b ig ored if f(T – S) do s not provide a res lt

whic , rou ded to one decimal, is at le st 0,1 dB This is the case for (T – S) > 19,5 dB

For the re der’s con enien e, Ta le 3 provides n merical values of the contribution of s stem

noise, rou ded to one decimal

6.2 Determination of the c r ent noise index A

1

The c r ent noise in ex in a freq en y decade, A

1, is determined by the q otient of the

c r ent noise voltage in a freq en y decade, E

c, over the a pl ed d.c voltage U

T

The mathematical in ex A

1

′ is b sed on dividing the c r ent noise voltage an d.c voltage

with pro er con ideration of the multiples of their u it volt, whic with their logarithmic

in exes C′ an D is presented as

where

C′ is the logarithmic in ex of the c r ent noise voltage, s aled at 0 dB = 1 V;

D is the logarithmic in ex of the d.c voltage U

is b sed on dividin the c r ent noise voltage an d.c voltage in their

in ivid al u its an multiples, whic with their logarithmic in exes C an D is presented as

A

1

= C − D

where

C is the logarithmic in ex of the c r ent noise voltage, s aled at 0 dB = 1 µV

The diferen e of 12 dB b twe n the two in exes A

Ap lyin the definition of f(T − S) from a ove (se 6.1), le d to the fol owin stan ard

eq ation for the determination of the c r ent noise in ex A

calc late the c r ent noise in ex A

1

The fol owin sp cial con ideration a ples

If the me s red total noise a pro c es the me s red s stem noise, hen e if

(T − S) < 1,0 dB

an th s the ac urac of the determination deteriorates, it is not recommen ed to u e this

method for the determination of a c r ent noise in ex A

UE

10dB21

⋅

=A

UCNR

6.4 Ac urac

The ac urac of the noise voltage me s rement s al b ± ,7 dB The ac urac of

determination of the c r ent noise in ex s al b ±1 dB when the c r ent noise is large

comp red to the s stem noise, i.e (T − S) is gre ter than 15 dB

It is not u common for certain resistors to ex ibit noise me s rement variation gre ter than

0,7 dB It s ould therefore b recog ized that lack of agre ment of re e ted me s rements

on s c resistors do s not neces ariy reflect a los of ac urac of the me s rin s stem, but

is an in ication of a noise pro erty of the resistor

6.5 Req irements

Ac e tan e criteria for the c r ent noise of tested prod cts s al b given with referen e to a

req ired maximum c r ent noise in ex A

1

in the relevant comp nent sp cification

Su h ac e tan e criteria s ould b stated throu h a fixed maximum value, typical y given as

fu ction of the sp cimen resistan e

7 Information to be given in the relevant c mponent specification

When this test is in lu ed in a relevant comp nent sp cification, the folowin detai s s al b

given as far as they are req ired or a pl ca le:

Subclau e

The dis ip tion to b provided throu h the a pl ed d.c voltage 5.3.4, Ta le 2

A l mitation to the a pl ed d.c voltage, if a plca le 5.3.4, Ta le 2

The relevant comp nent sp cification s al sp cify for its own purp se:

Non-dimen ional fig re re resentin the are of a p s -b n in a

gain-over- req en y diagram

Annex X

(informativ )

Cross-reference for references to

the prior revision of this standard

The revision of this stan ard has res lted in a new clau e n mb rin Ta le X.1 provides

cros -referen es b twe n the clau e n mb rin of this edition comp red to the first edition of

th in ic te v lu s of R

T

Bibl ography

IEC 6 0 7 (al p rts), Lete r symb ols to b e used in ele ctricaltech olo y

IEC 6 617, Grap hical symb ols for dia rams

MIL-STD-2 2G, Method 3 8 “Curre tNoise Test for Fix d Re sistors”, 19 1

G T Conrad, Jr N Newman, A.P Stan bury, “A Recomme ded Sta dard Resistor-Noise

Te st System”, IRE Tran action on Comp nent Parts, Volume CP-7, p 1-18; Se temb r

19 0

Hameg In truments, Profes ional Article “Wh t is n ise ”, 2 0

N Newman, G T Conrad, Jr “Dis ussio of e rrors of a Recomme ded Sta dard

Resistor-Noise Te st System”, IRE Tran action on Comp nent Parts, Volume CP-9, p 18 -19 ;