Author Topic: USB 3 Type C routing on small extension board  (Read 1417 times)

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Offline Jackster

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USB 3 Type C routing on small extension board
« on: December 03, 2018, 05:23:25 pm »
I have a small PCB where we are extending out the USB Type C connection.

Require someone to route the trances from one Type C plug to a Type C socket.
Only need 5gbps and would prefer a 2 layer board to a 4 layer.



PM me with quotes.






 

Offline podericof

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Re: USB 3 Type C routing on small extension board
« Reply #1 on: December 20, 2018, 09:17:15 am »
Hi Jackster,
I strongly discourage to use 2 layers. I would use strip lines.

1. with microstrip you'll get an impedance error between 10% and 20%  from the expected value due to the fabrication process in PCB. while when you use stripline the error is usually around 5%
2. don't forget that during the EMC testing, you may be asked to do the radiated emission up to 6 GHz due to the high-frequency clock you are using. And stripline gives you a better EMC shield.


I had a quick look at your layout below and my suggestion is to increase the spacing between the GND copper and any controlled impedance traces.
For example, if you see your PCB, the first 2 differential tracks (from the top) you have one track near a large GND copper. You need to expect on that track to have a lower impedance of the nearby tracks.

also, don't forget that GND planes(or land) on different layers tends to oscillate if you don't have enough vias ( set the vias pitch at labda 4), in your case, at least one vias each 2.54 cm

Good luck,


 
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Online wraper

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Re: USB 3 Type C routing on small extension board
« Reply #2 on: December 20, 2018, 09:45:04 am »
2 layers won't fly. It will become a radio transmitter killing bluetooth, wifi and wireless mouses in close proximity. Not to say in will cause problems to signal integrity.
 

Offline Jackster

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Re: USB 3 Type C routing on small extension board
« Reply #3 on: January 30, 2019, 12:39:50 am »
Still searching for someone to re-design this PCB for me.
 

Offline rahandford

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Re: USB 3 Type C routing on small extension board
« Reply #4 on: February 14, 2019, 05:37:40 pm »
May be able to help. 2 layer at your risk. rupert_handford@mr3design.net
 

Offline timgiles

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Re: USB 3 Type C routing on small extension board
« Reply #5 on: February 14, 2019, 07:12:57 pm »
Set the gap between trace and ground to 5x trace width at least

The diff pairs should be length matched - but that is each pair not all pairs. Looks like you are trying to match all traces length.

4 layers. 2 will always have issues when you are low on routing area

Try to put the meanders after the traces have become mismatched in length. They are there to bring the transmissions back in sync.

Good luck
 


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