As I said, I'm doing this project to learn. I like to explore all the alternatives.
In my electronics classes I learned about FET's, so I was more familiarized with them, so I went with them first.
The OTA seems like a very nice device after I gave it a look. I read the LM13700 datasheet, it has a lot of circuit examples, including a VCF (2 pole). But I know nothing about this device, is there any basic tutorial, explaining how they work?
Another thing, for simulating circuits, what simulator do you use? I am currently using Multisim 10, but it doesn't have a lot of parts and I don't like it very much.. Are there any better alternatives?