Ideal Balun ADS - RF Cafe Forums
Post subject: Ideal Balun ADS Posted: Thu Dec 29, 2005
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 are:
Balun1 found under Passive-RF Circuit
Balun2 found under Passive-RF Circuit palette
found under System-Passive palette
Balun4 found under System-Passive
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 in ADS??
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
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
Post 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.
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.
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
Post subject: Posted:
Mon Jan 09, 2006 1:08 pm
I'm sorry, I'm just extremely sensistive.
I am also right!
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
Mike already mentioned in his second post
he was not seeing a good match.
You guys need to lighten
up and just admit..YOU GOT SERVED!