Op amp transfer function determination ()

In summary, the conversation is about a problem with an active low pass filter and a second setup which also functions as a filter. The person is trying to find the transfer function Vout/V1-V2 and needs help understanding how to incorporate both setups into the equation. They are also advised that having two input sources allows for deriving two different transfer functions and that the problem can be solved by subtracting both functions.
  • #1
android25ua
1
0
OP warned about not using the homework template
Hey guys, need help with a problem here.

Sorry for the quality of the image.

2q0r6tg.jpg


I understand that above the op-amp, is the active low pass filter. So if I were to figure that out with respect to V2 and Vout, it would just be

Vout/Vs = -(Zf/Zs)

where

Zf = (Rf/(1+jwCfRf))
Zs = Rs

But I don't understand how the bottom setup comes into the equation. I realize it must also be a filter and should be solved wrt V1.

And I am asked to find the transfer function Vout/V1-V2.

All help would be greatly appreciated.
 
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  • #2
Because you have two input sources you can derive two different transfer functions (one inverting and the other one non-inverting).
And - as a second step - it should not be a problem to substract both functions Vout=Vout1-Vout2.
 

1. How do I determine the transfer function of an op amp?

Determining the transfer function of an op amp involves analyzing the circuit and using mathematical equations to calculate the relationship between the input and output voltages. This can be done by identifying the feedback network, finding the open-loop gain of the op amp, and applying the appropriate equations.

2. What factors affect the transfer function of an op amp?

The transfer function of an op amp can be affected by various factors, such as the type and configuration of the op amp, the values of the resistors and capacitors in the circuit, and the frequency of the input signal. Temperature and power supply voltage can also impact the transfer function.

3. Can the transfer function of an op amp be modified?

Yes, the transfer function of an op amp can be modified by changing the values of the resistors and capacitors in the feedback network. This can be done to achieve a specific gain, frequency response, or other desired characteristics.

4. How do I test the accuracy of the determined transfer function?

The accuracy of the determined transfer function can be tested by applying different input signals and comparing the output voltages to the expected values calculated using the transfer function. This can be done using a function generator and an oscilloscope.

5. Are there any common errors when determining the transfer function of an op amp?

Yes, there are some common errors that can occur when determining the transfer function of an op amp. These include incorrect calculation of the open-loop gain, incorrect identification of the feedback network, and not taking into account the effects of the op amp's bandwidth and slew rate. It is important to double-check all calculations and consider all factors to ensure an accurate transfer function determination.

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