# Help On Node analysis for filter interpretation

Joined Oct 5, 2018
34
Hi Guys,

I am writing with regards to the checking of my work! I tried to do some node analysis to churn out, hopefully, the transfer function of the circuit afterwards by using the equation solver in matlab. However, the results seem weird. Any advice?

Thank you in advance!

Joined Oct 5, 2018
34
additionally, if my purpose is to find the frequency that it is working on, is this the right way for me to go along with it? since my plan is to churn out the trf function and compare it with the general formula and do a coefficient comparison.

Thank you!

#### The Electrician

Joined Oct 9, 2007
2,866
additionally, if my purpose is to find the frequency that it is working on, is this the right way for me to go along with it? since my plan is to churn out the trf function and compare it with the general formula and do a coefficient comparison.

Thank you!
Why do you have different labels (v2 and v3) for the same node? What weird results did you get?

Joined Oct 5, 2018
34
Why do you have different labels (v2 and v3) for the same node? What weird results did you get?
hmm maybe my understanding is flawed and i should have just taken the values of the capacitors and inductors in parallel before establishing the node there for easier calculation.

unfortunately, my laptop is down for now but my coefficients were of the e15 values. Additionally sir, can i ask if it makes sense my proposal of doing the method of churning out a transfer function and comparing coefficients with the general formula to finally obtain and deduce the frequency in which the filter was operating at?

#### The Electrician

Joined Oct 9, 2007
2,866
hmm maybe my understanding is flawed and i should have just taken the values of the capacitors and inductors in parallel before establishing the node there for easier calculation.

unfortunately, my laptop is down for now but my coefficients were of the e15 values. Additionally sir, can i ask if it makes sense my proposal of doing the method of churning out a transfer function and comparing coefficients with the general formula to finally obtain and deduce the frequency in which the filter was operating at?
The coefficients I get range from e17 to e-22.

If you're using a math software like Matlab, it's easy to plot the transfer function and see the frequency range where the filter is working. If you need exact values for the frequency of certain features of the transfer function, you can use a numeric solver to get them.