Learning Forum

[james.fletcher]

Hi,

 

Can someone confirm for me how matched vs unmatched ports work?  From the help guide : "A matched terminal project is analogous to an unrenormalized wave port in driven modal where the s-parameter is referenced to the 'natural impedance' of the port cross-section. If you unselect Matched, you renormalize to a set impedance for the diff or common mode"

I understand this to mean if I go to excitations -> Differential pairs and tick the matched box, and use a wave port for a differential pair, the wave port will calculate the impedance at the port, and use this to normalise the S-Parameters.

Whereas if I left matched unticked, the S-parameters get normalised to the differential and common mode impedances I manually set in the differential pair menu?

 

Many thanks for any info

 

[Takeshi Itadani]

That is correct.
If you check Matched, the S-parameters are calculated using the differential impedance obtained from the analysis of the Wave Port surface.
If you do not check Matched, the S-parameters are calculated normalized by the Ref.Z set in Differential Pairs.