Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while tying up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
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My Hobby Website:
Ideal Balun ADS - RF Cafe Forums
RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media
platforms dominating public commenting venues. RF Cafe Forums began sometime around
August of 2003 and was quite well-attended for many years. By 2010, Facebook and
Twitter were overwhelmingly dominating online personal interaction, and RF Cafe
Forums activity dropped off precipitously. If the folks at
phpBB would release a version with integrated
sign-in from the major social media platforms, I would resurrect the RF Cafe Forums,
but until then it is probably not worth the effort. Regardless, there are still
lots of great posts in the archive that ware worth looking at.
Below are the old forum threads, including responses to the original posts.
|-- Amateur Radio
Gripes & Humor
-- CAE, CAD, &
Test & Measurement
Post subject: Ideal Balun ADS Posted: Thu Dec 29, 2005 5:11
What's the 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
Balun1 found under Passive-RF Circuit palette
found under Passive-RF Circuit palette
Balun3 found under System-Passive
Balun4 found under System-Passive palette
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 in ADS??
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.
Post subject: 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
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.
subject: Posted: Thu Jan 05, 2006 2:35 am
What's the matter? Is
that all you got?
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 page.
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 thoughts welcomed!!
Posted: Mon Jan 09, 2006 1:08 pm
I'm sorry, 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
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!