designing a LC bandpass filter

LC bandpass filter

hi designers,

i am a beginner in Rf design, will somebody advise/help me on designing a bandpass filter which the specs is as below using LC components.

Center frequency : 56.20665MHz
Bandwidth: 11 MHz,
Insertion Loss: 1dB
60dB attenuation at +/- 10 Mhz from the center frequency

Is there any particular topology that I should try on?

And can somebody pls suggest me a good software to design this type of filter (with option optimizer). I've been using ansoft sv and aade all this while..and they have not helped me much..

your help and suggestions are highly appreciated.thanks!

Hello,

The best way is to go to Nuhertz Filter solution product (**broken link removed**)

They have good synthesis tool for Lumped LC filters, you can get free Lite version or you can ask for 30 days trial license...
**broken link removed**

**broken link removed**

http://www.ebooksmechatronic.com/ebook_Filter/eBook_Filter.htm

---manju---

This is a tough filter requirement because you need at least 7 poles and will be hard to get good quality standard component values.

You will have to take the parasitic capacitance of the inductors (SRF) into account as well.

Hi all,

Thanks for your prompt reply.

Actually, I have tried to design this filter using elliptical (Cauer) topology. However, the result given by simulation (AADE software) is not at all the same as the result when i mounted on PCB. Kindly help me to understand the situation.

Herewith, I attached the schematic and results given by simulation and the real one.

Few remarks to help you to understand my problem:
1. This filter is designed for high power application (80W).
2. I alter the component values in the initial schematic such that I may use the inductors that already in my disposal. They are through-hole inductors and self-winded.
3. Hence, to compensate, the capacitors used in this schematic are not standard values, so I put few capacitors in parallel so that I can get the value that I want. They are Hi-Q ceramic capacitors and their voltage rating is 500V.

My questions:
1. What are other parameters that I should take care of in order to get a real good filter response? Is the thickness of PCB, component spacings play a part as well?

2. I obtained the free trial license for Filter Solution recently and have been 'playing around' with it a little bit. However, I couldn't find an option/menu where I can enter my own design (placing components without entering numerator/denominator). Does anybody know if this option is available with this software?

Merci beaucoup!