I'm finding myself needing to do a fair bit of analog filter design. Mostly passive LC ladder filters. I honestly don't know much about how to design them by hand, I've been using the Genesys tool.
I'm also getting into using a lot of free software for my work. I find the work flow is generally faster and more enjoyable. So, I've been looking for a free software analog filter design tool. It's quite easy to design digital filters with Python, but there doesn't seem to be much for analog filter design (and I mean choosing the values of capacitors and inductors).
So, am I missing something? Is it straightforward to realize an analog filter with these tools? If not, why does nothing like this exist? What are the typical algorithmic methods for designing analog filters?
*EDIT: What I mean is free as in freedom software. I'm aware of all the vendor provided tools, I don't like them. I usually find them much more difficult to work with. And, I'm also just curious now about why there doesn't seem to be much open software in this area.
Best Answer
There are a number of online tools though they are often limited. Here is a list of online and free desktop tools
Active filter web based tools
Active filter desktop design tools
Passive filters
Simulation
I would always recommend simulating the software generated filter with real life simulation models of the components you intend to use for your implementation.
Use a different simulation tool that the generation tool to limit the possibility of software bugs effecting your design.
If you are not dealing with purely sinusoidal signals remember to consider the step and impulse response.