I am working on a project involving PCB parasitic extraction and conducted EMI. I am still learning these tools, so my questions may seem basic, but I would really appreciate expert guidance.
1. Source and Sink Direction
When assigning source and sink in Q3D, do we need to follow the real current direction on the PCB, or can we place source and sink on any side on the net? If the direction is different from the real circuit, does it affect the results in twinbuilder?
2. Nets With Many Branches
If a net has multiple branches (for example, a power rail that goes to many components), where should we place the sources and the single sink? Also, if I put the sink at the input side and the sources at the component side, then in Twin Builder when I attach a voltage source at the input, will this cause any opposite or incorrect effect in the simulation?
3. How Many Nets Should We Extract?
Do we need to extract parasitics for every net on the PCB, or only for important nets like high‑speed signals, switching nodes, and sensitive analog traces? My PCB currently has no input‑side filter, so if I extract parasitics for the entire PCB, is this okay or not recommended?
4. Components Not Available in Twin Builder
When we import the Q3D equivalent circuit into Twin Builder, how do we handle components that are not in the Twin Builder library and do not have a model from the manufacturer? For example, how should we represent a microcontroller in the circuit?
5. Effect of Source–Sink Placement on Coupled Traces
If two traces are close to each other and have coupling, does the source–sink placement affect the extracted results in Q3D or the behavior in Twin Builder?
6. Do Source and Sink Affect Only Extraction or Also Twin Builder Results?
Are the source and sink assignments used only for calculating parasitics in Q3D, or do they also affect the results after importing the circuit into Twin Builder?
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