Hello. Here is my task:



How to solve this? I'm confused because of only one input in opamp.

 

Not necessarily an opamp; it's just an amplifier with a gain of "A."

 

We are studying opamps right now so it's probably opamp
I started thread by mistake here, it should be in homework category...

 

We are studying opamps right now so it's probably opamp

It really doesn't matter what you think it is. It's a generic voltage gain block.

 

If it helps you visualize the circuit, think of it as a non-inverting opamp stage, with the R2-C2 node connected to the + input.

ak

 

Hello. Here is my task:

View attachment 94943

How to solve this? I'm confused because of only one input in opamp.

Hi,

What you would do is first write out the transfer equation which of course includes the gain A, then solve for the A that makes one or more of the poles cross the jw axis into the right hand plane of the complex frequency plane. The input doesnt even matter that much but you probably assume that is a stable input, like a unit step.

I have to assume that you know how to write the transfer equation or i could not see how this question could have been asked of you, unless you missed a lecture or something

 

To find loop gain, we cut feedback and apply test generator like this:






Then we use conditions Re{Abeta} >=1, Im{Abeta}=0, to find A, right?

 

I got A=6.7 ...

 

Yes, your answer is good. But can you show as your work?

 

Of course.