Chapter 2 Analog Signal Conditioning

8/17/2019 Chapter 2 Analog Signal Conditioning

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Industrial Instruments 1Industrial Instruments 1Chapter 2Chapter 2

Analog Signal ConditioningAnalog Signal ConditioningDr. Bassam KahhalehDr. Bassam Kahhaleh

Princess Sumaya Univ.Princess Sumaya Univ.Electronic Engineering Dept.Electronic Engineering Dept.


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Princess Sumaya University

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#nalog Signal $on itioning #nalog Signal $on itioning

ObjectiveOb

jectiveIntro uce the %asic techni&ue o' signalIntro uce the %asic techni&ue o' signalcon itioning in process control.con itioning in process control.


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DefinitionDefinitionSignal con itioning re'ers to operationsSignal con itioning re'ers to operationsper'orme on signals to convert them to aper'orme on signals to convert them to a'orm suita%le 'or inter'ace (ith other'orm suita%le 'or inter'ace (ith otherelements in the process-control loop.elements in the process-control loop.


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rinciples of Analog Signal Conditioningrinc

iples of Analog Signal ConditioningSignal-)evel an Bias $hangesSignal-)evel an Bias $hanges)ineari*ation)ineari*ation$onversions$onversions

$urrent Signal +4 , ! m#$urrent Signal +4 , ! m#Digital Inter'aceDigital Inter'ace

/iltering 0 Impe ance/iltering 0 Impe anceatchingatching

)oa ing)oa ing

!"

#"

!$ # %

Sensor "


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assive Circuitsassive CircuitsDivi er $ircuitsDivi er $ircuits

)oa ing e''ect o' )oa ing e''ect o' ))

)) !!

# 1

# 2 # %

! S

! D


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assive Circuitsassive CircuitsDivi er $ircuitsDivi er $ircuits

Sel'-heating +Sel'-heating + !! is a temperature sensoris a temperature sensor

ExampleExample6 S 7 2 6

1 7 1 K 8

4 K8 9 ! 9 1! K8 1.43 6 9 6 D 9 !.:3 6

.21 m; 9 P D 9 .5! m;

# 1

# 2

! S

! D


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assive Circuitsassive CircuitsBri ge $ircuitsBri ge $ircuits

;heatstone Bri ge;heatstone Bri ge

# 1 # 2

# 3

! D

# 4

V R R

RV

R R R

V 42

4

31

3

+−+=∆

3241 R R R R =


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;heatstone Bri ge;heatstone Bri ge=alvanometer Detector =alvanometer Detector

# 1 # 2

# 3

! D

# 4

! &h

# &h

a b

a

b

# '

'alvanometer


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;heatstone Bri ge;heatstone Bri ge)ea $ompensation)ea $ompensation

# 1 # 2

# 3

! D

# 4

a b

c


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;heatstone Bri ge;heatstone Bri ge$urrent Balance Bri ge$urrent Balance Bri ge

# 1 # 2

# 3

! D

# 4

ab

# (I

# 4 )) # (

*# 2+# 4, )) # (

5542

54

31

3 )( R I V

R R R R R

V R R

RV −++

+−+=∆


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;heatstone Bri ge;heatstone Bri gePotential easurement Using Bri gesPotential easurement Using Bri ges

# 1 # 2

# 3

! D

# 4

ab

! c - ! " + ! a

042

4

31

3

=+−++ V R R R

V R R R

V xc

! "

0)(

5542

54

31

3 =−+++−+

+ R I V R R R

R RV

R R R

V x


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assive Circuitsassive CircuitsRC RC /ilters/ilters

)o(-pass)o(-pass RC RC /ilters/ilters

)2/(1 C R f c π =

#

C ! out! in

2

1

1

+

=c

in

out

f f V

V

/

'ain

/ 0

1


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)o(-pass)o(-pass RC RC /ilters/ilters$asca e Stages$asca e Stages

# 1

C 1 ! out! in

/

'ain

/ 0

1

C 2

# 2

)2/(1 C R f c π =2

1

1

+

=c

in

out

f f V

V

%oading ffect # 2 )) # 1 C2 C 1


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"ample 2 11"am ple 2 11 # measure signal has a 're&uency @ 1 KA* # measure signal has a 're&uency @ 1 KA*%ut there is un(ante noise at a%out 1 A*.%ut there is un(ante noise at a%out 1 A*.Design a lo(-pass 'ilter that attenuates theDesign a lo(-pass 'ilter that attenuates thenoise to 1C. ;hat is the e''ect on thenoise to 1C. ;hat is the e''ect on themeasurement signal at it ma . o' 1 KA*measurement signal at it ma . o' 1 KA*


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"ample 2 11"am ple 2 116out " 6in 7 . 1 at 1 A*6out " 6in 7 . 1 at 1 A*

' ' cc 7 1 KA*7 1 KA*Use $ 7 .4:Use $ 7 .4: FF//

7 33.> 7 33.> 88 +too small - too much current+too small - too much currentUse $ 7 . 1Use $ 7 . 1 FF// 7 12>1 7 12>1 88Stan ar 7 1.2 KStan ar 7 1.2 K 88

' ' cc 7 1 51 A*7 1 51 A* 6out " 6in 7 . >>>>26out " 6in 7 . >>>>2 #t 1 KA*G #t 1 KA*G 6out " 6in 7 .>>56out " 6in 7 .>>5


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Aigh-passAigh-pass RC RC /ilters/ilters

)2/(1 C R f c π =#

C

! out! in

2

1

+

=

c

c

in

out

f f

f f

V V

/

'ain

/ 0

1


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Ban -passBan -pass RC RC /ilters/ilters

# 5

C 5

! out

# %

C%! in

/

'ain

/ 2

1

/ 1

If / 1 / 2 &hen $ou use the individual e6uations for the % 7 and 5 7


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Operational AmplifiersOperational AmplifiersInverting #mpli'ier Inverting #mpli'ier

!out

# 1

! in

−

+

# 2

1

2

R R

V V

in

out −=


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Operational AmplifiersOperational Amplifiers?on Inverting #mpli'ier ?on Inverting #mpli'ier

! out

# 1

! in

+

−

# 2

1

21

R R RV V inout

+=

! out - ! in

! in+

−


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Operational AmplifiersOperational AmplifiersSumming #mpli'ier Summing #mpli'ier

!out

# 2

! 1

−

+

# 1

+−= 2

2

31

1

3V

R

RV

R

RV out

# 3

! 2


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Operational AmplifiersOperational AmplifiersDi''erential #mpli'ier Di''erential #mpli'ier

!out

# 2

! 2

−

+

# 1

)( 211

2V V

R

RV out

−=

# 2

! 1# 1


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Operational AmplifiersOperational AmplifiersDi''erential Instrumentation #mpli'ier Di''erential Instrumentation #mpli'ier

! out

# 3

! 2

−

+

# 2

)(2

1 211

21V V

R

R

R

RV

G

out −

+=

# 3

! 1

#2

−

+

+

−

# 1

# 1

# '


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Operational AmplifiersOperational Amplifiers6oltage-to-$urrent $onverter 6oltage-to-$urrent $onverter

IL

# 3

−

+

#1

in L V R R

R I

31

2−=

#2! in

# 4

# (

# %

42531 )( R R R R R =+


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Operational AmplifiersOperational Amplifiers$urrent-to-6oltage $onverter $urrent-to-6oltage $onverter

I−

+

#

#

! out IRV out −=


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Operational AmplifiersOperational AmplifiersIntegrator Integrator

! out

#

! in

−

+

C∫ −= dt V RC V inout 1


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Operational AmplifiersOperational AmplifiersDi''erentiator Di''erentiator

! out

#

! in

−

+

C

dt dV

RC V in

out −=


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Operational AmplifiersOperational AmplifiersPo(er SupplyPo(er Supply

! out

! in−

+

! CC

! CCt0

+! CC

− ! CC


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! out

! in−

+! CC

t

+! CC

0


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! out!CC

t

+! CC

0

! in

−

+

8 ! CC

8 ! CCH

−


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Chapter 2 Analog Signal Conditioning