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Solving for Transfer Function

tharper
4-Participant

Solving for Transfer Function

Hi All,

This may end up being a very simple question for some of you advanced folks.  I have been using Mathcad for years, but not always at a great depth, and somewhat sporadically. 

Anyhow, I was working through some circuits in the s-domain, and MathCad works really well here to quickly narrow down the equations...certainly faster than by hand. 

I have attached the file with my question at the very bottom of of the calculations. 

 

I would really like to solve this circuit for Vo/Vi to arrive at the s-domain transfer function.   Is there a one-step solver in Mathcad for this?  I know how to use the symbolic solver to find a solution for any single variable, but wondering if there is a way to find the expression for Vo/Vi?  

Please don't laugh too hard if I'm missing something obvious through my ignorance.  I have hunted through Mathcad's help and some of the other community entries out here and have not found anything like this. 

 

Thanks!

 

ACCEPTED SOLUTION

Accepted Solutions
Werner_E
25-Diamond I
(To:tharper)

6 REPLIES 6
tharper
4-Participant
(To:tharper)

Doh!  Never mind...I see that I have an extra term in the numerator that is screwing me up. This circuit has offset and I missed this term before writing my question.  My mistake. 

 

Anyhow, faults aside with my initial question, is there a way to directly solve for an expression like Vo/Vi if I didn't have this extra term?  

 

Thanks

Werner_E
25-Diamond I
(To:tharper)

Maybe that way:

B.PNG

tharper
4-Participant
(To:Werner_E)

Very slick!  Thank you for the help!

tharper
4-Participant
(To:Werner_E)

Werner, this solution has given me a powerful tool in my MathCad arsenal, and is exactly the help I needed in properly using MathCad for this solution.  Thanks for taking the time to share! 

 

-MF-, Very sorry I have not been available to post a circuit...my priorities were shifted to a different project and I have not been able to get back to this.  As I said, I found a couple of errors in my original equation, but with my most recent solution, it seems to track the actual circuit.  If I get the chance, I will still come back and post to satisfy your (and my) curiosity.  

-MFra-
21-Topaz II
(To:tharper)

Hi,
something does not convince me. Could you add a copy of the circuit?
Thank you.

tharper
4-Participant
(To:-MFra-)

Yes, of course.  I found an error in my initial calculations, but will fix it and re-send with a pic of the circuit.  I am away from the office today, but will attempt to put something together for you here. Thank you. 

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