ForçaCelta wrote:
Hello,
I am designing a radio receiver and I need a narrow filter in the FI
stage,
at 10.7 MHz, in order to filter a single carrier.
Anybody could tell me where to get information about designing ladder
filters?
Thanks

The latest ARRL handbook comes to mind. Have you web searched?

It is often profitable to choose a frequency at which you can get lots
of inexpensive crystals -- it's often cheaper to buy and sort through a
bag of 50 cheap crystals than it is to order four custom made ones,
unless you're counting the value of your time.

And if you _are_ counting the value of your time, you'll just want to
buy a crystal filter, or a whole dang radio!

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html