ads balun

Hi, when simulating a 50 Ohm impedance balun. Which setup is right?

The next question is, what is the impedance looking into one of the balance ports? I guess it should be 50/2 for differential signal, am I right?

If I am right, then if I design 2 identical circuit blocks connecting to the 2 balance ports of the balun, for matching, should each of the circuit blocks have a 25 Ohm input impedance ?

Thanks

the 1st setup is ok , specially the balun is 50 ohm balanced output

khouly

All the three configurations are correct. It defers from the output load impedance only. the important thing is both setup 1 and 3 are identical in all aspects like impedance phase char etc. Setup 3 aloows you to simulate for phase and gain imbalances if any.

If you need further clarification please PM.

I guess I can answer my own question now:

Both setup 1 and 3 are correct. Setup 1 test the differential s-param at the balance ports. and setup 3 test the single-ended s-param. Result from setup 3 can be converted to the mixed-mode s-param by some equations.

Yes you are right,
Also setup 2 is one form of transformer which is referenced to GND. It is no more called as Balun.