Finding v0 in an Ideal Op-Amp Circuit

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In summary, the homework statement is trying to find an expression for v0 in terms of vA,vB and the resistance values. The ideal op-amp circuit shown in figure can be used to find an expression for v0. The rules governing ideal op-amps are used to solve for v1. The input impedance is 0 or Infinity depending on the other facts in the amplifying circuit.
  • #1
surajalok
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Homework Statement


Analyze the ideal op-amp circuit shown in figure to find an expression for v0 in terms of vA,vB and the resistance values.


Homework Equations


if i label the voltage across R1 as V1
then vi know that v1=R1/(R1+R2) *v0
but i need one more expression for v1.
i tried to use kvl in the lope (with Va,Ra and R1) but couldn't solve because of resistance Ra



The Attempt at a Solution

 

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  • #2
What are the two basic rules governing ideal Op-Amps? (Hint: Use the voltage one, not the current one)
 
  • #3
what do u meen with use Use the voltage one?
i tried using kvl on all the loops but coudn't solve.
current goin into the + on the amp =0 and voltage is 0 between + and - on the amp. summing point constraint.
 
  • #4
The voltage at each of the op-amp's inputs is = V1. It's just a fact about ideal op-amps.
 
  • #5
is there any way to show that
How about noninvering amp?
But then should i use KVL at amp node=
 
  • #6
The current going into each input = 0 and the voltage is the same at each input. It's true for inverting and non-inverting.
 
  • #7
And one more question in an amplifing circuit is the input impedance =0 or is is it infinity
or does it depend on the other facts.
We have a voltage source directy connected to + or - on the amp
but it woulden't be op-amp's inputs is = V1. for noninvering amp because R1 doen't exist in non inverting.
 
  • #8
Well, I think I have given you too many free answers haha.

Just use Ohm's law and you can figure out the input impedance. I = V/R. To get 0 current, your R must be ?

Then you would have the same voltage on the other input if it is directly connected, they are always the same.
 
  • #11
i just want to know why the get Rin =0
because WesleyPipes said i=v/R
I=0 if R=--->infinity or if v=0
we know that v is zero
but R can't be zero
 
  • #12
Calculation is simple.

Va-V1)/Ra + Vb-V1)/Rb = 0
Solving, V1= [(Va/Ra) + (Vb/Rb)] / [(1/Ra) + (1/Rb)]

Now, Vo = [1+ (R2/R1)]V1
Substitute and you will get the answer.
 

1. What is a non-amplifying circuit?

A non-amplifying circuit, also known as an operational amplifier (OP), is an electronic device that takes in an input signal and produces an output signal that is the same as the input signal. It does not amplify the signal, but rather performs mathematical operations on it, such as addition, subtraction, and integration.

2. How does a non-amplifying circuit work?

A non-amplifying circuit consists of an inverting and non-inverting input, a power supply, and a feedback loop. The input signal is compared to a reference voltage at the inverting input, and the output signal is determined by the difference between the two inputs. The feedback loop adjusts the output signal to maintain a stable state.

3. What are the applications of non-amplifying circuits?

Non-amplifying circuits have a wide range of applications in electronic devices, such as audio amplifiers, filters, and signal conditioners. They are also used in instrumentation and control systems, as well as in medical equipment and sensors.

4. How do you choose the right non-amplifying circuit for a specific application?

The selection of a non-amplifying circuit depends on the specific requirements of the application, such as the desired gain, bandwidth, and input/output impedance. It is important to carefully consider these factors and consult data sheets and application notes to choose the most suitable circuit.

5. Can a non-amplifying circuit be used as an amplifier?

No, a non-amplifying circuit is not designed to amplify signals. It is designed to perform mathematical operations on the input signal without changing its amplitude. However, it can be used in conjunction with other components to create an amplifier circuit.

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