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

• DaniilMP3
In summary, the conversation discusses building a circuit for a given operation on three voltages. The circuit uses a voltage summer and integrator to calculate the capacitance and resistance needed. The negative capacitance is caused by the signal being inverted by the op-amp based Miller integrator. It is also mentioned that the conversation is related to a homework assignment.
DaniilMP3
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:

We'll use circuit of voltages summer:

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

Than, calculate capacitance:

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

And here we have -44 kilo Ohm for R_2.

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)

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