Can't see the error in the transfer function

In summary, the conversation is about a student's confusion with a problem involving transfer functions and bode plots. They mention deriving the transfer function and filling in a table, but are having trouble with the phase plot. After some edits and calculations, the student realizes their mistake and the problem is resolved.
  • #1
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Homework Statement



Here is the problem:

Screen Shot 2015-01-18 at 2.24.54 PM.png

Screen Shot 2015-01-18 at 2.25.07 PM.png


Homework Equations

The Attempt at a Solution



Okay so I was REALLY confused as to why something wrong happened. Here is my work for the whole question:

IMG_0492.jpg

IMG_0493.jpg


Sorry for the terrible writing.

Okay so for part a), I derived the transfer function as required. I had to be careful about the impedance of the capacitor though. Then I went to fill in the table and I got the results displayed above.

It appears the bode plot information in part a) is correct by looking at part b), which indicates a high-pass.

What doesn't make any sense though is the phase plot. The phase characteristics I found in part b) are clearly correct, but do not match up to part a) at all.

I have been staring at this for an hour now and I can't see what's going wrong. Could someone shed some light on this?

Thank you.

EDIT: Please note for part a), I computed the phase ##\Delta \phi## by using:

##\Delta \phi = - \text{arctan}(\frac{\omega}{\frac{10^6}{1.2}})##

EDIT2: Wait wait I think I figured it out, I forgot about the ##90^o## angle for part a), so that would mean:

##\Delta \phi = 90^o - \text{arctan}(\frac{\omega}{\frac{10^6}{1.2}})##

EDIT3:

Never mind guys, everything appears to make sense now that I fixed the phase characteristic.

Thank you anyway.
 
Last edited:
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  • #2
Zondrina said:
Never mind guys, everything appears to make sense now that I fixed the phase characteristic.

Thank you anyway.
No worries! It's always satisfying to sort out a problem yourself.
 

1. What is a transfer function?

A transfer function is a mathematical representation of the relationship between the input and output of a system. It describes how the output of a system changes in response to a change in the input.

2. How do I know if there is an error in the transfer function?

To determine if there is an error in the transfer function, you can compare it to the expected output of the system. This can be done through simulation or by analyzing real-world data. An error in the transfer function may result in discrepancies between the predicted and actual output of the system.

3. Can an error in the transfer function be corrected?

Yes, an error in the transfer function can be corrected by identifying and correcting any mistakes in the mathematical representation or by making adjustments to the system itself. It is important to accurately identify and correct any errors to ensure the system operates as intended.

4. What are the consequences of an error in the transfer function?

The consequences of an error in the transfer function can vary depending on the system and the severity of the error. In some cases, it may result in inaccurate predictions or incorrect functioning of the system. In more critical systems, such as those used in medical or aerospace industries, an error in the transfer function could have serious consequences.

5. How can I validate the accuracy of a transfer function?

There are several ways to validate the accuracy of a transfer function, including performing simulations, conducting experiments, and comparing the predicted output to real-world data. It is also important to thoroughly review and test the mathematical representation to ensure it accurately reflects the system's behavior.

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