Design an opamp circuit with this transfer function on 3 voltage inputs

Click For Summary

Discussion Overview

The discussion revolves around designing an operational amplifier (op-amp) circuit that implements a specific transfer function involving three voltage inputs. The focus includes the use of a voltage summer and an integrator, as well as calculations for component values such as capacitance and resistances.

Discussion Character

  • Homework-related

Main Points Raised

  • One participant outlines the need to create a circuit that performs a specific operation on three voltages, mentioning the use of a voltage summer and an integrator.
  • The participant raises a concern about calculating capacitance, suggesting that the result indicates negative capacitance, and questions whether this is feasible or if an error has occurred.
  • Another participant notes that the negative sign in the output is due to the nature of the op-amp based Miller integrator, which inverts the signal, and suggests that an additional inversion may be necessary to correct this.
  • Participants confirm that this is a homework-related question.

Areas of Agreement / Disagreement

There is no consensus on the feasibility of negative capacitance or the correctness of the calculations presented. Multiple viewpoints exist regarding the handling of the negative sign in the integrator output.

Contextual Notes

The discussion includes unresolved aspects such as the assumptions behind the calculations and the implications of negative capacitance, which remain unclear.

DaniilMP3
Messages
2
Reaction score
0
TL;DR Summary: Build a circuit of given operation on voltages

I'll appreciate any help.
I need to create circuit of this operation on three voltages:
CodeCogsEqn (1).png

We'll use circuit of voltages summer:
Screenshot_2.png


The third term is the integral of U_3, so we'll use integrator:
Screenshot_3.png


Than, calculate capacitance:
CodeCogsEqn (4).png

And on this step we have negative capacitance. Is it possible? Or I did something wrong?
Next, we calculate R_1, R_2.
Screenshot_4.png

And here we have -44 kilo Ohm for R_2.
 
Physics news on Phys.org
Welcome to PF.

Is this homework?

The negative sign comes from the simple op-amp based Miller integrator inverts the signal. If you want to cancel the negative sign, you will need to invert the signal in that branch, before or after the integration.
 
Hi, yes. This is homework. Thank you for your response.
 
Last edited:
DaniilMP3 said:
Hi, yes. This is homework.
(Thread moved to the schoolwork forums)
 

Similar threads

Engineering Why is the voltage source high potential into node 1 at -12 V in this op amp problem?
  • · Replies 15 ·
Replies
15
Views
2K
Any advice to make this Op-Amp temperature controller circuit work?
  • · Replies 34 ·
2
Replies
34
Views
4K
Time domain equation for RC circuit with AC input
  • · Replies 4 ·
Replies
4
Views
2K
How to determine drain-source voltage for this MOSFET amplifier.
  • · Replies 0 ·
Replies
0
Views
2K
Why does amplifier sink power for Vout>0 and sources power for Vout<0?
  • · Replies 1 ·
Replies
1
Views
2K
Engineering Circuit input impedance with ground in an OP Amp circuit
  • · Replies 4 ·
Replies
4
Views
3K
Calculating the voltage in an OP-amp circuit with a current source
  • · Replies 1 ·
Replies
1
Views
2K
Investigating the Effects of a Common Emitter Amplifier
  • · Replies 7 ·
Replies
7
Views
2K
How Can an Op-Amp and Diode be Used to Convert 12V to 5V for a PIR Detector?
  • · Replies 13 ·
Replies
13
Views
3K
From differential equations to transfer functions
  • · Replies 5 ·
Replies
5
Views
3K