Category: Software
Hello
I wonder if there is an open-source (or online) tool that can synthesize an analog filter to specification and have a Laplace function as output.
Thanks.
Hello
I wonder if there is an open-source (or online) tool that can synthesize an analog filter to specification and have a Laplace function as output.
Thanks.
We have a filter wizard program here: www.analog.com/filterwizard.
It will not generate a laplace function for you directly, but you can figure it out indirectly by doing the following:
1) Go to the stages view to get the natural frequency, Q, and gain for each stage:
2) The filter wizard gives the natural frequency in Hz, while you want it in radians for s domain work, so multiple by 2*PI. This is now your ω0.
3) Now plug in the values into each stage to the corresponding 1st or 2nd order filter formula in the laplace domain. For example, lowpass 2nd order formula is this:
You can see the formulas for all the 2nd order filter types here on pages 8.8 and 8.9:
https://www.analog.com/media/en/training-seminars/design-handbooks/basic-linear-design/chapter8.pdf
Yes the tool takes inputs exactly like you say:
However it is a tool for generating active analog filters. We've put limitations on it if the user requests something an active analog filter can't do well. I could see this interfering with what you want to do.
So in the specific example you cited, the tool only supports up to 1MHz passband for high pass filters. Above that op amp performance makes all the ideal highpass filters look like bandpasses in reality.
Another potential drawback if you are attempting to use this tool to generate digital filters: we limit the output to 10th order. When using active analog filters, really high order stages aren't practical for size, power, and component tolerance reasons.
