Learning Forum

[Reza]

Hello,

I'm new to Ansys SiWave and would appreciate some assistance.

When defining a port for a pair of group pins (e.g., Vcc group and GND group), SiWave prompts you to set the reference impedance of the port. How does this reference impedance affect the results (e.g., SYZ solver)? I believe the reference impedance is only used for S parameter measurement as port termination for non-driven ports, as explained in the video below. Is this correct, and is it not used for Y and Z parameter measurements?

https://innovationspace.ansys.com/courses/courses/intro-to-multiport-analysis/lessons/intro-to-port-based-network-analysis-methods-s-z-y-and-abcd-parameters-lesson-3/

Regards,

Reza,

[Mrinmoy Bharadwaj]

Hello Reza,
Thanks for reaching out. 
The reference impedace of the port here refers to the impedance of the source at which the energy is fed into the system. This reference impedance comes from the basic definition of scattering parameters at a port. It is desirable that this impedance is kept equal to the input impedance of the system to ensure maximum power transfer between source to the system. Usually for transmission lines a 50Ohm value is chosen as most transmission lines are designed for 50 Ohms but there are exceptions as well, where other values might also be used. You can find more details in the S-parameter technical notes in the help document of SIwave. Hope this helps in your understanding.