# Get transfer function from electrical scheme [closed]

Is there any software/SPICE tool in which I can draw electrical circuit and after that, software prints the transfer function in Laplace domain?

I will find this kind of tool very helpful and purposeful. I know how to derive it on paper an how to get bode/nyquist plot in software, but sometimes circuits are complex and could take me an hour or so just to get the transfer function.

Thanks :)

## closed as off-topic by Leon Heller, Daniel Grillo, Majenko, Chetan Bhargava, Matt YoungJun 16 '14 at 1:50

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## 2 Answers

Well, to my knowledge the best way to do this is to get a bunch of input voltage / output voltage values (in a .cvs for instance), and then to modelise that values by a function, using a software as for example LatisPro.

I don't know software doing this with symbolic computation, but I think it would be somehow the best way.

• I used to do this to check linearity of a system. Loaded the values into an Excel spreadsheet and used fitting to get an approximation of the trendline formula. Works great. I had a program that generated and gathered the data using NIDAQ cards. The problem starts if you have more complex dependencies like in freq. – user34920 Jun 15 '14 at 15:09

Use some toolbox (ex TINA) in order to get a plot for "frequency response" (mag /phase) for this circuit / system. After, pick a control (signal / systems) texbook. Go to the chapter something as "Obtaining transfer function from frequency response plots".

• I think op's problem is not having the formula with the numbers but having the formula with component values as parameters. Something you look at and you say "oh well I'd just double $R_x$ in order to move that pole a bit down". – Vladimir Cravero Jun 15 '14 at 17:05