LAUNCHXL-CC1310: Sharp bends on the RF path of the CC1310 LP

Savinda Gunawardena

Part Number: LAUNCHXL-CC1310
Other Parts Discussed in Thread: CC1310

Hi,

I'm trying to copy the RF routing on the CC1310 Launchpad and have noticed two bends (one 90 degree one just as it leaves a component and another 45 degree bend just before the trace leading to the UFL connector) on the RF path. Shouldn't this be an issue for an RF signal? Is the 90 degree bend OK since it is at the end of a capacitor?

Also I noticed that the width of the RF trace varies from 0.3 as it leaves the RF_P and RF_N pins on the CC1310 to 0.4 as it comes out of the balun. Is this to account for the increased gap between the traces and the copper ground plane?

As you can probably tell, I am by no means an RF expert, so if someone could explain this to me I'd be incredibly grateful!

Thanks again!

over 8 years ago

0 TER over 8 years ago

TI__Guru**** 317180 points

- Track width: It's no specific reason why the track width is different width. The tracks are very short so it will nor make any difference if you use 0.3 mm or 0.4 mm.

- Bends: Yes, if a trace change direction 45 degree corners should be used. But this is not that important if the track changes direction out from the pad since the component is in 3 dimension and the track is in 2 (The signal changes direction within the component).

0 Savinda Gunawardena over 8 years ago in reply to TER

Intellectual 965 points

Thank you TER. So does this mean that we can do a 90 degree bend at the exit of a component on the RF path? This would mean that I do not need to make a mitered bend right?

0 TER over 8 years ago in reply to Savinda Gunawardena

TI__Guru**** 317180 points

Yes as long as the 90 degree bend is made in the component pad as in the ref design.

0 Andrew G over 8 years ago in reply to TER

Intellectual 900 points

My understanding is that in the sub-GHz range, there is no downside to 90 degree bends. See for example

www.montrosecompliance.com/.../corners-Japan.pdf

0 TER over 8 years ago in reply to Andrew G

TI__Guru**** 317180 points

Probably true since the wavelength is long compared to length/ width of the trace.

But if you have space for a 45 degree angle you can use it.

Sub-1 GHz

Sub-1 GHz forum

LAUNCHXL-CC1310: Sharp bends on the RF path of the CC1310 LP