Ideal Balun ADS - RF Cafe Forums
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Below are all of the forum threads, including all
the responses to the original posts.
Post subject: Ideal Balun ADS Posted: Thu Dec 29, 2005 5:11 pm
component for IDEAL balun in ADS...there are a few and i'm not sure which one to use. I need to convert both
ways....single to diff. and diff. to single. The components I found are:
Balun1 found under Passive-RF
Balun2 found under Passive-RF Circuit palette
Balun3 found under System-Passive palette
Balun4 found under System-Passive palette
Balun1 and Balun2 don't seem ideal because they involve
transmission line parameters and frequency parameter. Balun1 and Balun2 seem to be for diff. to single conversion
but again they don't seem ideal.
Balun3 seems like single to differential but Balun4 has differential ports
on both sides. I can use Balun3 for single to diff. conversion but what about diff. to single conversion? Do you
use Balun4 for that but it has diff. ports on both sides....should i just connect my diff. signal on one side and
take out the unbalanced signal from the other side leaving one port 'open'??? Is there any other balun component
Post subject: Posted: Thu Dec 29, 2005 6:55 pm
Any response?? I
thought I might try Balun3. Is it ok if I use Balun3 component in ADS like the image below. also, should this
setup give me matched condition to 50 Ohm. I ran the simulation and didn't get exact match to 50 Ohms so I was
wondering if something is wrong here with the balun setup. also does any one know how to use zin() function within
the schematic in ADS. thanx
Post subject: Posted: Sat Dec 31, 2005 2:15 am
I believe the 2 outputs should be 25ohms.
Posted: Tue Jan 03, 2006 7:26 am
No, I think your setup is correct...you specify an impedance for the ideal
balun: i.e. Zo=50 and this will set each port to 50 ohms. since one port is grounded on the single ended side, you
will terminate the other port to 50 ohms....that's what i think
subject: Posted: Wed Jan 04, 2006 3:21 am
Well, I think you're wrong. For the same reason a power splitter
requires a 2:1 tranformer at it's intput.
If the BALUN was being used with a balanced output it would
require a single 50ohm resistor from output+ to output-. That's because it's a 1:1 balun.
Post subject: Posted: Thu Jan 05, 2006 2:35 am
What's the matter? Is that all you
You're lucky there's a Moderator here!
Post subject: Posted:
Sat Jan 07, 2006 11:52 am
No need to fight here although. DisAgree and you're on the wrong
This setup will not match as it is given (and will match if 25 Ohms each is on the differential side)
but I think the guy wanted to know about ideal Balun in general and I think his setup would not correctly tell
what the Balun is doing because he's grounding the differential side impedances. Isn't that right? If there was an
actual balanced output and each side of the balanced output was matched to 50 Ohms and then an ideal balun was
used to convert the balanced to single ended then I think you will terminate it in 50 Ohms and not 100 Ohms.
So, the setup shown by the guy, yes it's wrong and will not match unless impedance on the differential side
sums up to 50 but I think the guy was asking what would actually happen if one tries to convert a balanced output
that has its each side matched to 50 Ohms to single ended. In that case you do terminate in 50 Ohms. Rod your
Post subject: Posted: Mon Jan 09, 2006 1:08 pm
I'm just extremely sensistive. I am also right!
Post subject: Posted: Mon Jan
09, 2006 2:16 pm
Hi guys. I have an opinion, but shan't present it here because level heads do not prevail.
Here's a simple empirical solution to determine who is correct:
Connect a 50 ohm source to TERM2 and look
at the VSWR with 50 ohms on each of the differential ports, and then with 25 ohms on each differential port.
Whichever setup results in a 1:1 VSWR wins.
Post subject: Posted: Mon
Jan 09, 2006 2:34 pm
Yeah, you can do that if you want to burn precious calories.
mentioned in his second post he was not seeing a good match.
You guys need to lighten up and just
admit..YOU GOT SERVED!