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Single ended to differntial LPF - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


ljoseph
Post subject: Single ended to differntial LPF Posted: Wed Aug 19, 2009 3:02 pm

Captain


Joined: Tue Sep 04, 2007 7:54 am
Posts: 13
Location: Dallas
Hi,
I have calculated the values for a 230 Mhz LPF for single ended configuration with source and load impedance of 100 ohms. I want o convert this filter to differential. How to convert the L and C values from single ended to differential?

Single ended filter values (5 pole butterworth)
L1=30nH
L2=16nH

C1=29pF
C2=27pF
C3=6pF


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Paul Chriss
Post subject: Re: Single ended to differntial LPFPosted: Mon Sep 21, 2009 10:41 pm

Captain

Joined: Sat Mar 04, 2006 10:12 am
Posts: 8
I swear I don't work for them, but I just did a Google Search and found this program that does the job.

http://www.appliedmicrowave.com/Filter1B.htm

Maybe you can downlaod a trial version?


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Alberto
Post subject: Re: Single ended to differntial LPFPosted: Wed Oct 07, 2009 6:05 pm

Captain

Joined: Sun Oct 04, 2009 5:17 pm
Posts: 6
The 4 series inductors (2 for each branch of the differential filter) value will be equal to the single ended value divided by 2. In your case
L1a = 15 nH
L1b = 15 nH
L2a = 8 nH
L2b = 8 nH
Capacitors, instead, will keep their original value:
C1 = 29 pF
C2 = 27 pF
C3 = 6 pF

Best regards,
Alberto



Posted  11/12/2012
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