Electronics > PCB/EDA/CAD

Differential impedance calculation

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Vilius:
Zo is really the sign for single ended impedance? I know what single ended impedance is, but ideally, single ended impedance should be 45 Ohms is my goal is to have Zdiff of 90 Ohm, this Saturn thing keeps getting worse and worse xd

thm_w:
Please read the links above, and use the tooltips in Saturn.

Your goal is Zdiff 90, not Zo 45

nctnico:
Ideally you'd need 2 lines with Zo =45 Ohms. On a 1.6mm PCB you are looking at traces nearly 3mm wide and then you'll need distance between them to make  differential pair... It will be hard to get this PCB designed and likely the rule-of,thumb formulas used by Saturn are way outside their usefull limits. A better option is to use a 4 layer pcb with thin dielectrics between the outer and inner layers.

Damperhead:
I wouldn't worry too much about the impedance. I would try to keep the differential wiring as short and clear as possible and the return current path as good as possible. It can be challenging with 2-layer PCB. However, you will probably have to add protection components between the differential pair, so the impedance will hardly be the desired 100 Ohm +/-10% on the transmission lines.

Sagar:
various impedance calcualtors are there but I will always recommend to use the one given by the PCB manufacturer because they know the quality, core, prepag much more then a random tool. You can find the listed one in the capabilities section, or on web listed by them.
example: https://jlcpcb.com/pcb-impedance-calculator

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