Analyze this opamp active filter circuit

Click For Summary

Homework Help Overview

The discussion revolves around analyzing an operational amplifier (op-amp) active filter circuit, specifically focusing on determining the function Vs/Ve. Participants are exploring various methods to approach the problem, including the application of Kirchhoff Current Law (KCL) and the use of complex analysis.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the use of KCL equations for analyzing the circuit and express uncertainty about whether to simplify resistors and capacitors or to apply KCL directly. There is also a suggestion to explore both methods for verification.

Discussion Status

Some participants have provided guidance on using KCL and have requested the formulation of specific equations. There is an ongoing exploration of different approaches, and while some equations have been presented, there is no explicit consensus on the correctness of the methods used.

Contextual Notes

There is mention of potential sign convention errors in the equations presented, indicating that assumptions about the circuit setup may need to be revisited. The discussion also highlights the complexity of the problem, with participants considering both phasor and differential equation methods for analysis.

ace130
Messages
8
Reaction score
0
Hello, so this the circuit of an IdeaI OPAMP.
R7Umlxl.jpg

The Question is to find the function Vs/Ve .
I tried to make some sum ups to simplify it but I still unable to find a solution, so I tried to NOT sum up any component and found this:
E-S=iZ+i2(Z+R)
E=iZ+i3R
S=i2R

so the idea is to find E=f(i2) , This is the final Result but I'm not sure if it's correct :
50QjLNT.jpg
 

Attachments

  • R7Umlxl.jpg
    R7Umlxl.jpg
    7 KB · Views: 974
  • 50QjLNT.jpg
    50QjLNT.jpg
    11.1 KB · Views: 881
Last edited by a moderator:
Physics news on Phys.org
ace130 said:
Hello, so this the circuit of an IdeaI OPAMP.
View attachment 219618
The Question is to find the function Vs/Ve .
I tried to make some sum ups to simplify it but I still unable to find a solution, so I tried to NOT sum up any component and found this:
E-S=iZ+i2(Z+R)
E=iZ+i3R
S=i2R

so the idea is to find E=f(i2) , This is the final Result but I'm not sure if it's correct :
View attachment 219619
I'm not quite sure what you are doing with your equations, but are you familiar with how to solve circuit problems using the Kirchhoff Current Law (KCL) equations? I would write the KCL equations for the two nodes in the middle (the - input of the opamp and the middle connection point between the 3 capacitors), and solve those simultaneous equations for the gain of the circuit s(t)/e(t).

Also, are you supposed to be solving this with phasors or differential equations?
 
Yes i know the KCL , also this should be solved in complex .
I don't know if I should sum up those Rs and Cs or just write KCL that will take more time
 
ace130 said:
Yes i know the KCL , also this should be solved in complex .
I don't know if I should sum up those Rs and Cs or just write KCL that will take more time
I don't know of a technique to "sum up" the Rs and Cs, but there may be one. Why not do it both ways to check your answer?

Can you show us the two KCL equations that I mentioned? Then show how you would solve them simultaneously...
 
this is the KCL and loops
frLP0ia.jpg


and this is the final result:
50Ri9vs.jpg

Edit : the final line it should be Zc not 1/Zc .
 

Attachments

  • frLP0ia.jpg
    frLP0ia.jpg
    29.6 KB · Views: 355
  • 50Ri9vs.jpg
    50Ri9vs.jpg
    28.9 KB · Views: 339
Your equation (2) is not right. It suffers from a sign convention error.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 1 ·
Replies
1
Views
5K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 16 ·
Replies
16
Views
4K
Replies
16
Views
4K
  • · Replies 9 ·
Replies
9
Views
7K
Replies
8
Views
2K
Replies
8
Views
3K
  • · Replies 6 ·
Replies
6
Views
1K
  • · Replies 16 ·
Replies
16
Views
2K