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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*
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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
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)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
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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:
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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
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@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:
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1!!! 1!!!! 1!!!!! 1!!!!!! 1!!!!!!!!
2
'
;
1!
12
3EF 8 % ! M '95
3EF 8
reIuency Nlot /O4ain o3 1!! /it, )nput
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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>
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erio- to ea>
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"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-
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erio- to ea>
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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;
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O(
+@VEE=Va( R2R1+R
2)=
V
VEE(0.49920.00045 ) 8 %9!!0 !9!!5;