Full chip simulation in HFSS

Hi All,

My circuit is Differential and operate with 100 ohm. Now I am doing Full chip EM simulation with HFSS. On that i got the different s-parameter values when i set the lumped port impedance as 50 ohm and 100 ohm. So which value i have to set for correct EM simulation on my differential circuit?


Thanks in Advance.
Karam

Hi All,

Can anybody suggest, how much impedance have to be set for lumped port in any circuit ... ?

Is that impedance depends of circuit impedance or not...?

Hi,

If you want to have a differential port, you have to set the impedance to 100 ohm. The thing is, by setting your differential port's impedance to 100 ohms, you will miss the common mode response. So, my suggestion is to have two single ports with impedance of 50 ohms (instead of one differential port with impedance of 100 ohms) and then use mixed mode formulas to extract the differential S parameters from single mode S parameters.
Anyway, setting the impedance of a differential port to 100 ohms is correct.

Hi,

I run the simulation with HFSS 100 ohm impedance( include everything 100 ohm- ../imgqa/eboard/Antenna/rf-da45b2wkgtt.jpg ). the result of s-parameter simulation is same with as 50 ohm.

From that result i get either differential circuit or single end circuit, no need to bother in HFSS simulation at lumped port. It does not affect the overall value of my circuit.

Is that right...! FYI i attach the image URL

Clicking your URL (in green) opens your image OK.

It Means do i no need to bother about HFSS lumped port impedance, either my circuit differential or single end...?