ensc 225 operational amplifier lab

7/25/2019 ENSC 225 Operational Amplifier Lab

1/15

Laboratory #1: Operational Amplifer

Circuits

ENSC 225 MicroelectronicsLab roup 2!

"y:

arry $raaisma %&!12&'5&'

(aful )slam &!121*5*2

+,ali- .a,/as, &!1101'5

(an-eep S,a,i &!122'1*


2/15

or all t,e 3ollo/in4 eperiments6 t,e rail 7olta4es across all op%amps /ere

measure- to beVcc 8 129!'2 !9!!''!;' < an-

VEE 8 %129!&* !9!!''!*'

es t,e O=set CurrentIOS 8 |IB1IB2| 8 !9!& !9!'2 nA

Circuit 2


3/15

)n Circuit 26 /e carrie- out t,e same proce-ure as in Circuit 1 an- came up /it,

sli4,tly -i=erent results:

R 8 !900*0 !9!!!0;05 M

B,e output 7olta4e6 /,ic, 3or reasons state- abo7e is t,e O=set


4/15

t,at no-e an- 4roun-6 t,ere is no 7olta4e -i=erence across t,e resistor an-

t,ere3ore no current o/s t,rou4, t,at branc,9 B,is means t,e frst o3 t,e )nput

"ias Currents can only o/ t,rou4, t,e in7ertin4 input an- t,rou4, t,e 1Me4

resistor9

B,ere3ore6 t,e )nput "ias Current t,rou4, t,e in7ertin4 input IB1 8 VO

R1M 8

%295!2 !9!!10 DA

B,is ma>es t,e )nput "ias Current IB=IB

1+IB

2

2 = 19251 !9!!!05 DA

As /ell6 t,is ma>es t,e O=set CurrentIOS 8 |IB1IB2| 8 295!2 !9!2! DA

B,ese su--en increases in ma4nitu-e may also be eplaine- by t,e lar4e 4ain o3t,is particular circuit conf4uration9

Comparing these results with the Data sheet:

rom t,e frst t/o circuits /e can see t,at our eperimental O=set no/ eactly /,y our eperimental 7olta4es matc, t,e i-eal

temperature -ata /,ile our eperimental currents -o not6 but t,eories can ran4e

3rom more precise testin4 eIuipment use- by t,e manu3acturer to t,e 3act t,at /e

-i- not use pulse tec,niIues to 4ain our measurements6 /,ic, t,e -ata s,eet says

may cause Junction temperature to c,an4e9

Experiment 2

Circuit with Gain of 10

Bo ac,ie7e t,is circuit /e use- t,e 3ollo/in4 resistors:


5/15

Ri 8 2915!' !9!!12*52 >

Rf 8 K09;' !9!!02& K09;&' !9!!01*F > 8 109; !9!1&;' >

"ase- on t,e circuit conf4uration t,is 4a7e us a calculate- 4ain o3 1+R f

Ri=

1!9152 !9!!;'

B,e circuit /as t,en assemble- as t,e sc,ematic seen belo/:

B,is circuit an- input create- t,e 3ollo/in4 3reIuency response:

1!!!! 1!!!!! 1!!!!!! 1!!!!!!!!

2

'

;

1!

12

3E5F 8 % !5 M ;90*

3E5F 8

reIuency Nlot /O4ain o3 1! an- )nput


6/15

@sin4 linear analysis 3ormula on t,e latter ,al3 o3 t,e -ata6 /e can -etermine t,e

@nity ain reIuency 3B/,ere amplitu-e eIuals 1P9

Circuit with Gain of 100

Bo ac,ie7e t,is circuit /e use- t,e 3ollo/in4 resistors:

Ri8 !90;& !9!!!0&15 >

Rf 8 K2915!5 !9!!12*525 K295'& !9152*15 K*9!5 !9!5&525F > 8

059*'&5 !92!*51 >

"ase- on t,e circuit conf4uration t,is 4a7e us a calculate- 4ain o3 1+R f

Ri=

0;912; !922

B,e circuit /as t,en assemble- as t,e sc,ematic seen belo/:

B,is circuit an- input create- t,e 3ollo/in4 3reIuency response:


7/15

1!!! 1!!!! 1!!!!! 1!!!!!! 1!!!!!!!!

2

'

;

1!

12

3EF 8 % ! M '95

3EF 8

reIuency Nlot /O4ain o3 1!! /it, )nput


8/15

B,e calculations o3 t,e 7olta4e le7els an- perio- 7alue can be 3oun- in Appen-i 19

B,e calculate- 7olta4e le7els an- perio- are:

ea> to ea>


9/15

erio- to ea>


10/15

"elo/ are t,e /a7e3orms o3 t,e circuit 4at,ere- 3rom an LBSpice simulation9 B,e

4rap, also contains 7alues t,at /ill be use- to calculate t,e simulation perio- 7alue

an- 7olta4e le7els9 Note t,e no-e?s names correspon- to t,e same no-es in t,e

sc,ematic pro7i-e- in t,e lab outline9

erio-


11/15

erio- to ea>


12/15

No/ /e /ill loo> at t,e oscilloscope measurements 3or t,e same no-es9 )n t,e le3t

oscilloscope capture6 t,e top /a7e3orm is t,e /a7e3orm at No-e A an- bottom

/a7e3orm is t,e /a7e3orm at No-e "9)n t,e ri4,t oscilloscope capture6 t,e top

/a7e3orm is t,e /a7e3orm at no-e " an- t,e bottom /a7e3orm is t,e /a7e3orm at

no-e C9 A4ain t,ese correspon- to t,e no-e names 4i7en in t,e lab outline9

Appenix 1: Calculation of Relaxing !scillator

B,e measure- 7alues o3 all components are as 3ollo/s:

C8 0902! n

R1 8 1'9*2! !9!!0& >

R2 8 1'9*& !9!!0&&5 >

R3 8 09;2! !9!!01 >

Assume no c,ar4e is in t,e capacitor be3oreVcc an-

VEE are applie- to t,e op%

amp an- all suRes re3er to sc,ematic 4i7en in lab outline9 B,e 7olta4e -i7i-er

bet/een (1 an- (2 ma>es t,e 7olta4e at t,e non%in7ertin4 input:

+@VCC=Va( R2R

1+R

2)=

V

Vcc(0.49920.00045 ) 8 9!11 !9!!5;


13/15

O(

+@VEE=Va( R2R1+R

2)=

V

VEE(0.49920.00045 ) 8 %9!!0 !9!!5;

ensc 225 operational amplifier lab

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