Operational Amplifier: Op-Amp as Differential Amplifier or Op-Amp as subtractor (With Examples)
In this video, how to use the op-amp as the differential amplifier (Difference amplifier) or as subtractor has been discussed with solved examples.
Op-amp as Differential Amplifier:
The differential amplifier is the op-amp configuration in which the difference between the inputs is amplified by some gain factor.
An Op-amp itself is a differential amplifier in open loop configuration but it has very high open loop gain. So, we can not use the opamp as the differential amplifier in the true sense in the open-loop configuration. And we require some sort of feedback to use this op-amp as a differential amplifier in the true sense.
Application of Op-Amp as differential Amplifier:
Apart from performing the mathematical functions, this differential amplifier configuration is used along with sensors. (e.g RTD)
The only disadvantage of this differential amplifier is that its input impedance is relatively low and depends on the series resistance used with the inputs. And in some case, it might affect the source voltage because of the loading effect.
The loading effect of the source can be avoided by using the buffer before applying the input voltages. And this method can be used for general purpose applications. For more sophisticated applications with sensors, instrumentation amplifier is used instead of the differential amplifier.
The timestamps for the different topics covered in the video is given below:
1:00 Op-amp as Differential Amplifier
6:30 Application of Differential Amplifier
9:35 Example 1
11:30 Example 2 (Effect of Biasing Voltages on output)
13:31 Example 3 (For practice )
This video will be helpful to all students of science and engineering in understanding how to use an op-amp as the differential amplifier.
The link to the related videos on the op-amp:
Introduction to Operational Amplifier:
• Introduction to Operat...
Inverting Op-Amp:
• Operational Amplifier:...
Non-Inverting Op-Amp:
• Operational Amplifier:...
This video will be helpful to all the students of science and engineering in understanding the inverting and non-inverting summing amplifier.
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The video solution of the practice problem : kzread.info/dash/bejne/qaqs1JSweMnSorQ.htmlsi=ta8xrg-VeGlfZ5rb The timestamps for the different topics covered in the video is given below: 1:00 Op-amp as Differential Amplifier 6:30 Application of Differential Amplifier 9:35 Example 1 11:30 Example 2 (Effect of Biasing Voltages on output) 13:31 Example 3 (For practice )
@hitman2754
5 жыл бұрын
I face problem "in seeing resistance from this side " the input resistance is this ? Which video should I watch
@hitman2754
5 жыл бұрын
Sir please reply 🙏🙏🙏
@jatinbhatt7826
2 ай бұрын
14:00 it can also be solved by knowing the fact that all resistances have equal value and therefore it works as an adder ckt at both inverting and non inverting terminals. Hence V+ and V- can directly calculated as 9v and -5v .
For those who don't know whats RTD : Resistance thermometers, also called resistance temperature detectors, are sensors used to measure temperature. Many RTD elements consist of a length of fine wire wrapped around a ceramic or glass core but other constructions are also used. The RTD wire is a pure material, typically platinum, nickel, or copper.
@uniqueeducationcorner975
Жыл бұрын
Thank you brother your comment helped us
The homework problem solution is 4V..... individually solving the inverting part as well as the non inverting part and then summing them up together... It was a good exercise indeed....Thanks a lot and grateful for all these intuitive videos, saves hours from scattered and motionless studying...
The answer is 4V. While calculating ....Rf = 1kiloOhm and Ri = 1 KiloOhm parallel 1 KiloOhm = 0.5 kiloOHm. And while calculating the voltage by the non-inverting input first use voltage divider (you will get 2V, 2.5V) then superposition theorem (consider the other two resistors as in parallel) ( 1 + 1/(1 parallel 1)) x (2V + 2.5 V) = 3V. Then at last V output because of that ( 1 + Rf/Ri ) x (3V) = 9 V. From inverting terminal we get Vout = -5V. So, the final answer if 9V + (-5V) = 4V.
@yonatantamiru7756
Жыл бұрын
on inverting part we get vo1=-5volt and non inverting part weget vo2=9volt , in total giving 4 volts
@hitarthanandrohra8846
Жыл бұрын
how can both V(non - inverting) and V(inverting) terminals have different voltages? as per the virtual ground/short concept both V+ = V- in terms of magnitude provided there is nothing mentioned in the question that these both are not equal. According to the basics of Op amps, voltage at inverting terminal is always equal to voltage at non - inverting terminal
@roshan459
Жыл бұрын
@@hitarthanandrohra8846 oh, yeah!
@jatinchauhan6902
11 ай бұрын
Parallel me thori hai Bhai dono 1 k ohm
@taravanova
11 ай бұрын
@@hitarthanandrohra8846 I believe it is because the principle of super position is being used. In steady state, v+ and v- probably are equal. To solve the problem more easily, we calculate how the system would respond if various input voltages were grounded (giving different values for v+ and v-), then sum the results.
I watched this whole palylist of 32 videos and my concept of opamp is clwar now . I am not preparing for gate but i am in 1st year of electronics in IIT BHU .
I really love the op amp playlist. Everything is so simply explained.
Thank you sir.I learned about opamp easily from your videos.The answer of the example 3 is 4v.(V total =V1+V2+V3+V4=-2v-3v+4v+5v).
@voldemort7443
5 жыл бұрын
I am not getting this answer please help me
@vatsalagarwal2758
5 жыл бұрын
@@voldemort7443 -(1/1)*2 + -(1/1)*3 + (1+(1/1))*((1/2)*4) + (1+(1/1))*((1/2)*5) = -2 -3 +4 +5 = 4v
@voldemort7443
5 жыл бұрын
Ye 1/2 ka factor, jo last two terms me aaya h, wo kya parallel resistance addition ki wajah se h?
@vatsalagarwal2758
5 жыл бұрын
@@voldemort7443 haan video dhang se dekh samajh aajayega
@bharadwajkv4662
4 жыл бұрын
@@vatsalagarwal2758 the answer is 1v bro
answer is 4v .and i would also suggest u to put more questions of this type for practice.
@harindudilipa1559
3 жыл бұрын
Hey can u explain me im stuck i cant find the answer
@waraysplayground26
3 жыл бұрын
Yeah, I got that answer by using nodal analysis. Lesser solutions... First, I solve the voltage at V+ using nodal which is 3V. Then, because it is a negative feedback V- = V+. So, voltage at V- is also 3V. Again, to solve for Vout, using nodal, the answer is: (2 - 3)/1k + (3-3)/1k = (3 - Vout)/1k, Solve for Vout, is 4.0V... ;')
@sukritihans8484
3 жыл бұрын
@@waraysplayground26 it might have been a typo, but ig that should be (2-3)*. Thankyou so much !
@priyanshagarwal5682
3 жыл бұрын
@@waraysplayground26 will Ra be equal to R1+R2?
@waraysplayground26
3 жыл бұрын
@@priyanshagarwal5682 , actually I didn't rely on the formula. I stick with the nodal analysis when answering op-amp. Ra is not equal to R1+R2 here. :)
Thank you SO MUCH for explaining this 9:20 diff issue. I spent too much time not understanding what the problem was in my circuit! Thank you!!!
I got 4 Volts which can be arrived at intuitively or using math. Here is my solution: This solution demonstrates that the total output is the sum of the outputs for each respective input. Vout = V2out + V3out + V4out + V5out Each output can be considered as 4 individual cases 2 cases for the Inverting Summing Amplifier and 2 cases for the Inverting Summing Amplifier. First consider the Inverting Summing Amplifier cases: V2out = - V2in x (Rf/R2) = -2Volts x ( 1/1 ) = -2 Volts V3out = - V3in x (Rf/R2) = -3Volts x ( 1/1 ) = -3 Volts In both cases the first term represents the input voltage, 2nd term the gain for each input voltage. Second consider the Non Inverting Summing Amplifier cases: V4out = + V4in x (Rg/ (Rg + R4)) x (Rf/R4 + 1) = +4 Volts x (1/2) x 2 = +4 Volts V5out = + V5in x (Rg/ (Rg + R5)) x (Rf/R5 + 1) = +5 Volts x (1/2) x 2 = +5 Volts Note, Rg represents the resistor tied to ground. In both cases the first term represents the input voltage, 2nd term the voltage divider, and 3rd term the gain for each input voltage. As mentioned earlier, the total output is the sum of outputs for each respective input. Vout = V2out + V3out + V4out + V5out Vout = -2 Volts - 3 Volts + 4 Volts + 5 Volts Vout = 4 Volts
@indrajeetkumar8917
Жыл бұрын
One resistance is already ground. If we tied to 5v resistance to gnd then the both resistance will be in parallel so the equivalent resistance will be 1Kll 1K= 0.5K
thank you very much for your perfect explanation your follower from EGYPT
@teja9017
4 жыл бұрын
Nice!
@varunv6309
4 жыл бұрын
Where u studied
for those who are not able to solve : consider the voltage Vx ( hope you know where is the vx) 2-vx + 3-vx = vx-vo vo =3vx-5 second equation 4-vx + 5-vx = vx vx= 3 put this value in first eq .
@manikanthbolem1328
2 жыл бұрын
thank you vroo
@chitrasingh9200
2 жыл бұрын
If it is right answer then video of summing amplifier is quite complex..superposition theorem,long equation
@shubham_2337
Жыл бұрын
@@chitrasingh9200 yeah true...no need to solve by superposition😇😇
@arshmohan4327
Жыл бұрын
bhaiya ji answer hi likh dete poora
@arshmohan4327
Жыл бұрын
@@manikanthbolem1328 bhai yeah bhi solve nahi hua tere se
Basically i am a maths student and tomorrow I have physics exam .... And the topic opamp is in it... I just see these videos and I have confidence that I am gonna pass... The explanation is too good and too easy to understand.... Love it so much ... And thank you....❤❤❤
@ALLABOUTELECTRONICS
6 жыл бұрын
Wish you all the best for exams.
Thanks for clearing Basic ideas. Answer of given problem is 4V.
I calculated in this way : V_out = - 2 - 3 + (1/2/(1+1/2))*(5+4)*(1+2/1) = 4 V. Thanks for this video !
After watching 4 op-amp videos, now I am addicted to the introduction music :))))
Sir the way you are teaching is very simple and the explanation is too good ...... Thank you so much sir 🎉🎉 The answer to the last que is 4v sir.
@Sofia-ee8vo
3 ай бұрын
Can you explain how you got 4v 🥺..
we can solve this problem by using summing amplifier. For inverting amplifier Vout= -Rf/R{v1+v2+v3} where R=same for all. similarly for non inverting Vout={1+Rf/Ra}×{v1+v2}/2. where R is same for all. Finally thank you sir for providing video. It is very clear to understand and learn.
@adjeifrancis6857
4 жыл бұрын
why v3 in the inverting amplifier?
@patrickfeeney4180
Жыл бұрын
Which resistor is Ra on this case?
Sol:- Resistors value is always 1 in question Applying super position theorom at uper node where (-) sign I2+I3=I1 (2-V)/1+(3-V)/1=(V-Vo)/1 5-2V=V-Vo -Vo=5-3V Vo=-(5-3V)-------1 Now apply down positive lower side superposition then I4+I5+I0=0(inside flow current is 0 in op-amp) Now, Voltage is same at both point according to rule (4-V)/1+(5-V)/1+(0-V)/1=0 -3*V=-9 V=3 Put the value in equation 1 Then Vo=-(5-9) Vo=4v Is correct ans
@antaradey1274
5 жыл бұрын
1v aa raha ha, Eqn 1 me for inverting- Vo1= 5 hoga,waha 5-3v kyu ho raha ha
@debangshudutta3567
4 жыл бұрын
yes it is correct
@dheerajkumarbaghel_0198
4 жыл бұрын
@@antaradey1274 yes
@sashipreetamnekkanti7799
3 жыл бұрын
why are you keeping solutions
I enjoy this music every time....it makes me happy😺
@mrtelcom4005
3 жыл бұрын
without understanding..?!😂😂😂
@nishapawar3368
3 жыл бұрын
@@mrtelcom4005 no...I understand these videos :)
Thank you so much! I always had trouble with understanding op amp circuits, makes perfect sense now!
@th3airraidsir3n5
5 жыл бұрын
Don’t know if you already have but would you make a video about RC parallel circuits? I have no clue what they do or how they work I want to understand from an AC standpoint as I am particularly interested in audio circuits.
I get 4V too. With love and respect from Shiraz
Thank u so much sir! I had trouble in linear circuits. By today my trouble was cleared. Once again tq sir!
Op-amp explanation is awesome sir , it helped me a lot .
answer is 4 , it seems easy by ur good explanation... Thanks sir
@prashikkhare14
2 жыл бұрын
V02 is at non inverting (1+Rf/R1) *vin So it is not 9v it's 18 . 18-5=13v
Answer is 4 v, using the superposition principal at each input,then find their superposition. Amazing content 💖
wow such a fine video.This is the best video I found on the topic.Thank You.
Ans 4v -2-3+4+5 = 4volts When consider 2v Vout = (-1/1)*2 which is 2V when 3v Vout = (-1/1)*3 which is 3V When 4V Vout = (1+(1/1))*V' where V' is get through voltage divider rule (Same resistance/Total resistance)*total voltage which is V' =(1/(1+1))*4 =2V so, when 4V consider Vout = 2*V' =2*2 =4V When 5V V' = (1/(1+1))*5 =5/2 =2.5V then Vout = (1+(1/1))*V' = 2*2.5 = 5V so total Vout = -2-3+4+5 =4Volts
@aadityavaidya1318
5 ай бұрын
Thank you boss 🫡❤
We can also follow basic method from where we derived basic formula (kcl+super position theorem)..ans 4.... thanks a lot for this valuable lecture
@sohamghag1726
9 ай бұрын
Correct bhai
Thank you Sir Amazing Explanation
Such a dedicated teacher u are
thank you sir i wil gate 4V and also thank you for this video series of (OP AMP)
Thank you...your videos are best. and Answer is 4v.
@shobhitpandey8821
5 жыл бұрын
Answer is 1 volt -5 from inverting input terminal and 6 for noninverting input terminal
@Harshavardhan-zr2ip
3 жыл бұрын
V3=0, V=(v1+v2)/2
Vout = 4V Through applying the superposition theorem for each input voltage.. We will get 4 output voltages.. Combining all these output voltage... The result will be = -2-3+4+5 = 4 V
@parvezmahmud6963
4 жыл бұрын
How? I guess, 1V Because the v3 (which is connected to the ground) of the non-inverting terminal has effect on the input voltages.
@greninja537
4 жыл бұрын
@@parvezmahmud6963 yeah 1 v is the answer
@SuPeRTRoNeRD
4 жыл бұрын
@@greninja537 Okay great, that is what my answer was as well. Thank you very much!
@prashikkhare14
2 жыл бұрын
V02 is at non inverting (1+Rf/R1) *vin So it is not 9v it's 18 . 18-5=13v
Here, to the ones who are struggling to get the answer, the answer is 4V, you get -5V from V1 and +9V from V2, add them together you get 4V
@synecdocheanimacion9021
8 ай бұрын
how can someone struggle to solve that really I'm cse 1st year that too in a private college still I was able to it solve it mentally... in the internals itself they ask questions much harder than this I wonder what they will ask in endsem 🙂
Best video in you tube, thank you so much
your teaching skill is great.. we need more videos upon electronics
u completely rocked and made me understand a concept in practical manner instead of sticking only to theory❤❤❤❤
And thanks for helping us by such a great teaching style
For inverting terminal inputs, one can also use summing amplifier concept to find output. Anyways thank you so much AAE.
A huge thnxxxx to uh sir.......i dnt hv words to express how much ur video lectures had helped me ....uh hv made electronics so easy nd interesting for.....student like...me.........😊😊😊....
Excellent.
Life saving, thank you
Sir ans Vout is 4V And tnks soouch for this all op amp concept explanation
@anushrigupta7539
3 жыл бұрын
Can you explain how you got 4V ? I literally got confused by seeing the circuit.
In the examples you have solved by using superposition i.e solving sources individually. These can be solved by using formulae derived for difference amplifier i.e. Vout= Gain ( V2-V1). And Gain = Rf/Ri
@prathamdabee7476
2 жыл бұрын
Can you show me how to do it
@prathamdabee7476
2 жыл бұрын
Please
The answer to the question is 4 volts
Thanks sir, I liked the way of teaching and explaining every bit in detail. Vout is 4V.
This video makes it more complicated than it has to be. Here's how to understand it simply: When you have an op-amp with a negative feedback, it will copy the voltage from + into -. *It's that simple*. All that's left is to figure out what the voltage on vout is.
thanks sir, I appreciate your method of teaching, answer is 4v, plz acknowledge
I dont know anything in analog electronics but now i am getting through it Thanks...
@aritradas9523
5 жыл бұрын
tere bhai jaisa koi hardich nhi hai
the videos are really good. the output voltage in the last question is coming as 4V for me...is it right?
@kishanprasadappana2093
3 жыл бұрын
Yeah
@AYUSHSINGH-pv3pl
3 жыл бұрын
yupp
Excellent explanation
Amazingly explained. Thank you so much !
Answer is 4v .. thanks man.. amazing video
in syllabus all cover to lecture for better understanding. these lecture are very good
Simple and precise explanation. Really superb👍Thank you✌️
Ans is 4V seems little late 😅 Great way of teaching Suggesting u to make videos on other parts of physics also it will be great 😄
4 v is ans.....great explanation
The intro music is very good...
Thanks alot for better understanding ans is 4v
Thank You sir :)
Great explanation of differential amplifiers.
never experienced such perfect explanation
excellent explanation. thank you sir.
Sir, we can also get the subtraction operation done by using the approximation R2/R1 >> 1 so that, 1+R2/R1 = R2/R1 and hence, Vo = (R2/R1)(V2-V1).
@phitsanuboy
2 жыл бұрын
Sorry for my newbie,I also confuse about R2/R1 >> 1, it mean 1+R2/R1 -> 1+1 = 2 the result difference between (R2/R1) -> 1 and (1+R2/R1) -> 2 quite a lot... In my thinking..
Sir if u provide videos on module based it will be added advantage... Any how your videos are like bible for electronics students and engineers too..
i got the actual proof from your video.thank you so much.what reference book do you follow ?
Getting equal gain means we have apply V2= R2/(R1+R2) That mean whatever the value is in the voltage.
Hi Sir thank you for such a nice series of lectures. Doubt are 8:07 Min Onwards 1. How Input impedance seen from upper terminal is R1 and lower is R1+R2. How? 2. Similarly at 8:24 Min how input impedance is 2R1. Thanks in advance.
@ALLABOUTELECTRONICS
2 ай бұрын
To find the input impedance at the upper terminal, just connect external source at that terminal. The ratio of that voltage to the current supplied by that source will give the input impedance seen through that source. And while calculating that, we will consider all other sources in the circuit as zero. That means the non-inverting terminal will get connected to ground via two resistors. So, if you apply the KVL at the inverting end, then you will get Vx / Ix = R1. Likewise, on the lower terminal, if you follow the same procedure, at the inverting end, you will get Vx / Ix = R1 + R2. Similarly, at 8:24, to find the input impedance, you need to find Vin / Iin. Because of the virtual ground, the voltage at the inverting and non-inverting node will be same. So, while finding input impedance, for simplicity, you can assume that both are connected together. So, whatever current (Iin) that is passing through upper resistor R1, same current will return through lower resistor R1 and will go back to the negative terminal of Vin. So, if you apply the KVL, then it is Vin = 2R1 *Iin. Or Vin / Iin = 2R1. I hope, it will clear your doubt. If you still have any doubt, then let me know here.
@satyaveersinghrawat4398
2 ай бұрын
@@ALLABOUTELECTRONICS Thank you for your response. I have solved all the cases according to your guidance and quite satisfied. For 8:24 Min, I am satisfied with the logic but still not able to figure out that what is happening with R2 which is connected between non-inverting terminal and ground. Current through that R2 will be 0, it is giving me a bit dissatisfaction even though I know solution is correct. Can I share the solutions (by any means), what I did, for crosschecking the correctness?
Since last week I am looking for the Answer How designer decide to use R1 and R2 at Non inverting terminal as Voltage Divider for achieving differential amplifier??! & I found here Thanks dear
@kishorgoodday276
3 жыл бұрын
From you i got answer , i made correct in v01 and gone wrong with v02 bcz i not use voltage divider now i got ...thanks dear
thankyou sir. my answer is 4v.
thank you Sir, very interesting.
Superb sir.....excellent explanation.....thanks a lot....
thank u you are genius good and very sharp
ans of last ques is 4 V and Thank U sir for this quality of lectures U r best
4V Sir, this video is very heelpful to me......thank u
Thanks bro, helps me lot.... 👍 you are the best
Ultimate explanation 🙌
Thanks, explained very nicely.
Your all video's are superb
Good 👍
The last example is more interesting than it looks. The feeback ratio for the inverting input is not the same as the non-inverting. The ratio for the non-inverting side is Rf/ (1k // 1k) => 1k/0.5k since we have at the inverting input two 1k ohm resistors in parallel to ground. When I first did this problem I got the wrong answer.
@tanujkasal
5 жыл бұрын
Thanx ,I was facing the same problem.
In the derivation part you considered resistance values are equal in the input of V2 and input of V1 and equal value as Rf.. But in the calculation part you have taken different resistance values for everything.. Is it necessary to take same resistance values for input of V2 and V1 and Rf?
@anon00089
9 ай бұрын
you've probably completed your degree by now, but if anyone else has the same question, this is just the method for derivations I'm pretty sure, you start with the general case and derive the particular cases (when input resistances are equal).
Really awesome and very informative videos... nice presentation and the groundwork is highly appreciable. The best KZread channel for those who want to go deep in to the World of electronics .👏👏👏 Thank you mannnnn!!!!!!💥💥💥💥
Awesome video sir! Thank you!
Thank you sir!
in the example1..v(out)=6v but if we apply the formula for v(out)=R2/R1*(v2-v1),ans=5v...or i am confusing about R2.. at 6:22 min u expalin this formula.U mean same value of R2 in the formula derived at 6:22 min.
Good tiching karte hai 👌👍👌👌👌👍
thanks you are great
great explanation, thank you!
It's so easy .I need more problems.😊😊😊
Very Good
hello @allaboutelectronics can you please comment me why V02 process of solving is different in example 1 and example 2 thanks for such an hard work
Is 4v the correct answer 🤔
thank you sir from phillipines
Thank you sir
Hi! what happens if V1 is fed with AC and V2 with DC? I am trying to solve an exercise in which V1 branch has a capacitor along with that 'R1', so I assume that when charged it releases DC but I am confused by how it works... seems like a band pass filter maybe?
@ALLABOUTELECTRONICS
3 жыл бұрын
Without looking at the circuit, it is difficult to tell the working of the circuit. But many different types of circuits related to opamp has covered and many examples have been also covered. You may check the opamp solved examples playlist. Perhaps you will find a similar type of example you are looking for.
@omarrz94
3 жыл бұрын
@@ALLABOUTELECTRONICS I'll check them! thank you
hello sir your analytical approach is perfect but when we do in simulation for 2nd example circuit the out is not 12v it is 10v
@ALLABOUTELECTRONICS
5 жыл бұрын
Because, often the saturation voltage of the op-amp is less than the biasing voltage. In fact, it's true for most of the op-amps. There are some rail to rail op-amps, whose saturationvoltage is close to biasing voltage. That's why you are getting 10v.
answer is 4V. Thank you sir i m enjoying your videos.
Ans 4v.sir u made this topic very interesting thank u