Variable center frequency filter

[metal]

Hello

Here we go guys, thank you all, I will be waiting for the analysis.

Any way, what analysis software you are using..

Thanks

[12 Cents]

Lots of opinions, I myself have no handy filter at hand now, had to search for myself, sorry...

[metal]

Hey 12 cents

No prob man , thanks any way..

[theChris]

i have uploaded the analysis to:
http://www.ee.siue.edu/~cstahl/e592b.pdf

at least that's what it should be. its just basic KCL equations (nodal analysis). there are some math tricks, but nothing difficult.

as you can see, for filter desing i prefer capacitive normalization where i choose a capacitor value then calculate resistor values around that.

from the same basic analysis you can find an equal value cap and resistor circuit with variable gain to change Q. i don't like this as much becasue the gain can be something goofy, and the circuit can oscillate with some gains.

[12 Cents]

There, now you got what you asked for

[metal]

Hey 12 cents

Yes, thats what I wanted, mathththththt, and the easy way to re-understand that was to print the 7 pages and start reading to recall what I studied earlier in uni. But this time in the real world

BTW, I will build the last circuit I posted this night, and will talk about results later

Thanks alot

[richie00boy]

Originally posted by theChris
As for the sallen key filters:
with a gain of 1, the circuit is resistively normalized -- if the resistors are equal value then the capacitors can be used to easily set the Q and Fc of the filter.

my preference is for a gain of 2. then the circuit is capacitively normalized -- if the capacitors are equal value the resistors can be used to easily set the Q and Fc of the filter.

i'll post the analysis later

I've downloaded your paper and look forward to some playing about with the ideas. Thanks!