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L Thnh Nhn 1Logo tm thi ca group , logo ny c mnh thit k da trn mu logo ca khoa .Logo c thit k vo nhng ngy u thnh lp cu lc b.SRAS Electronic Group l tn vit tt ca Studies and research electronic in applied science group .By gi logo ny khng cn ng chun lm ,nhng hin ti mnh vn khng c thi gian v tng nn mong cc bn thng cm .

Trng nhm : L Thnh Nhn .

1BME Lab GroupTm hiu v mch OpAmp

Mc ch ca bi hc : Bit c cu to v symboy ca opampKhi nim v khuch i vi sai .Cc thng s c bn ca 1 opamp .Cch c datasheet ca op-amp .Xy dng 1 mch opamp n gin .C th l mch sng ti n .

L Thnh Nhn BME Lab22I. Khi nim v OpAmp OpAmp : L vit tt ca cm t Operational Amplifier .L 1 mch tch hp ,s dng in p ngoi khuch i tn hiu .Vi h s khuch i rt ln .

L Thnh Nhn 3I. Khi nim v OpAmp Layout : i vi nhng mch tch hp ch c 1 b opamp th IC ch c 8 pins.V d nh LM358,LM741,y l nhng opamp thng dng .

L Thnh Nhn 4C nhng IC , bn trong c tch hp ti 4 b opamp th c ti nhng 14 pins.Vic tch hp nhiu module nh vy s gim kch thc mch in rt nhiu , gi thnh r , v hiu qu hn .Cng c nhng IC ch tch hp 2 module 2 th cng c , s chn vn l 8 , in hnh nh dng opamp TL082 .IC LM324 l dng opamp c cha 4 module bn trong, kiu ng gi (package) 14 chn , a mc ch , c s dng rng ri trong vic hc tp , nhng ng dng chung chung .4I. Khi nim v OpAmp K hiu trn mch nguyn l :

L Thnh Nhn 5Nhn trn mch, ta thy ngay con opamp ny c ng gi theo kiu PDIP 8 chn ,2 chn tn hiu, 1 chn xut , 2 chn ngun, v cn d 3 chn na , vy 3 chn cn d lm nhim v g nh ???Cc bn hy t suy ngh v tm cu tr li nh !!!

5II. Cu to ca Op-ampL Thnh Nhn 6

y l s mch cu to thnh opamp , mch tch hp cc linh kin bn dn gm c BJT (Transistor lng cc), in tr v t in .Hu ht cc opamp by gi u c thit k da trn mch ny .Nhn mch trn, nu cc bn hiu c th khng cn phi ni g thm- cc bn l thnh thuc hng ng cp ri .Cn nu khng hiu th cng ng nn vi bi quan , bi v ta chng cn phi quan tm n n lm ci nhim v qui g c .Mch trn mnh a ln ch yu l show hng t nhm uy hip tinh thn cc bn ngay t u .No c ln no !!!

6III. Cc thuc tnh ca Op-ampTrc khi miu t v cch hot ng ca opamp th trc tin ta phi tm hiu v cc chn , ngun cung cp nh th no .Voltage : Gm c in p vo, in p ra .Current: Dng chy vo, dng chy ra .V+ : Chn tn hiu vo khng o .V- : Chn tn hiu vo o .=> Chn out xut ra mc 1(high) khi v ch khi in p trn chn V+ ln hn in p trn chn V- .L Thnh Nhn 7III. Cc thuc tnh ca Op-ampNgun in cung cp cho opamp hot ng s quyt nh mc p ra ca opamp .Ty tng ng dng,m ta c th cp ngun n t 0 -> +Vcc (UNIPOLAR SUPPLY - 0v to Vcc) .Hoc cp ngun i (BIPOLAR SUPPLY +/-Vcc) .L Thnh Nhn 8Dng y , cc bn c bit ngun n v ngun i khc nhau nh th no khng ? Lm nh th no thit k c ngun i ???8III. Cc thuc tnh ca Op-ampHy phn tch cc v d sau :

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Mc p u ra thay i nh th no khi mc in p trn chn V+ c s thay i ???

9III. Cc thuc tnh ca Op-ampIf the"" input sits at half rail voltage via two equal-value resistors, the "+" input must go above V for the output to go HIGH, as shown in the animation below:

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III. Cc thuc tnh ca Op-ampThe "" input can control the output as shown in the animation below:

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From the animations above we have shown two things:1. The "+" input must be higher that the "" input for the output to beHIGH.2. A small increase in voltage on the "+" input (above the "" input) will change the output from 0v to approx full rail voltage. This representsHIGH GAINorAMPLIFICATION.11III. Cc thuc tnh ca Op-ampCc bn , hy c gng phn tch cc mch trn hiu r cch lm vic ca opamp !!!------------------------------------------------------------ng i kh khng kh v ngn sng cch ni m kh v lng ngi ngi ni e sng -----------------------------------------------------------L Thnh Nhn 12III. Cc thuc tnh ca Op-ampThe OP-AMP can be used as aVOLTAGE FOLLOWER. The output voltage follows the input.In this arrangement theopamp is called aBUFFERand has unity gain.The OP-AMP works like this:As the "+" input rises, the output rises.Normally the output would rise to rail voltage, but since it is connected to the "" input, it will always be a few millivolts below the "+" input.

L Thnh Nhn 13III. Cc thuc tnh ca Op-amp

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III. Cc thuc tnh ca Op-ampGain ( li khuch i) : y l h s khuch i tn hiu ra, ng ra s t trng thi bo ha khi in p Vout = Vcc .TheVoltage Gain(AV) of the operational amplifier can be found using the following formula:

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III. Cc thuc tnh ca Op-ampand inDecibelsor (dB) is given as: L Thnh Nhn 16

Th gin 5L Thnh Nhn 17

Th gin 5L Thnh Nhn 18

Th gin 5L Thnh Nhn 19

19Th gin 5L Thnh Nhn 20

20Th gin 5L Thnh Nhn 21

21IV. Khuch i v khuch i vi sai 1 . Khuch i l g ? Khuch i y c ngha l s phng i cc tn hiu ln (Maginifes signal). Tri tim ca mch khuch i chnh l ngun iu khin cc tn hiu u vo .

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IV. Khuch i v khuch i vi sai in p vo l V1, th ta c tn hiu vng h(open) V2 = k.V1 , k c gi l li vng h(open circuit gain). Trong 1 mch khuch i l tng th Ri = v cng v Ro = 0 (m).

L Thnh Nhn 23IV. Khuch i v khuch i vi sai => Mch khuch i vi sai y c ngha l khuch i nhng tn hiu sai lch c bin cc nh .

L Thnh Nhn 24IV. Khuch i v khuch i vi sai 2. Mch khuch i s dng BJT :

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IV. Khuch i v khuch i vi sai 2. Mch khuch i s dng BJT :S mch n gin ha nh sau : L Thnh Nhn 26

III. Cc thuc tnh ca Op-ampL Thnh Nhn 27