Tricks for (50Ohms) controlled impedance routing

Making PCB Layouts, Manual routing, Auto-routing, Copper pouring, Updating from Schematic, Manufacturing Output
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dieterv
Posts: 6
Joined: 16 Sep 2020, 09:37

Tricks for (50Ohms) controlled impedance routing

#1 Post by dieterv » 08 Oct 2020, 06:17

Hi,

I need to route a 50 ohms track between an SMA connector and a GNSS receiver module. Since the frequencies are rather high, the track should have a controlled impedance. I am going for a coplanar waveguide.

How I've done it so far:
* I have created a NET with a trace width of 45 mil, and 8 mil clearance. Combined with the specs that the boardhouse has given me, this should result in a fairly close match.
* I route the trace (routing mode with arcs).
* I add the impedance matching components (should these be required after production, I can add them)
* I then draw a copper pour connected to GND all over the trace. Since the NET asks for a 8 mil clearance, this is taken care of by the software.
* I then manually add plenty of static via's to the GP underneath, positioning them by eye.

I can't imagine that I'm the only one going through these steps. As soon as I have done all this, there's little freedom as to making (small) changes to the routing.
Has anyone come up with better ideas on how to manage this?

kalbun
Posts: 13
Joined: 15 Jun 2010, 18:34
Location: Italy

Re: Tricks for (50Ohms) controlled impedance routing

#2 Post by kalbun » 19 Oct 2020, 11:41

I think that, given the frequencies of the GPS, a coplanar waveguide surrounded by gnd vias is the best possibility.
"Scusate l'errore! E' che io questa convenzione dei segni non l'ho mai capita"
"Sorry for the mistake! Fact is, I still can't grab this current's sign convention"

(G.A. - assistant professor - lesson of theory of electronics)

dieterv
Posts: 6
Joined: 16 Sep 2020, 09:37

Re: Tricks for (50Ohms) controlled impedance routing

#3 Post by dieterv » 20 Oct 2020, 05:43

kalbun wrote:
19 Oct 2020, 11:41
I think that, given the frequencies of the GPS, a coplanar waveguide surrounded by gnd vias is the best possibility.
Thanks. It is also (as far as I know) the easiest to realize without going to a 4-layer board or specific dielectrics.
No tricks on how to do this in Diptrace?

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