Electronics World Cover,TOC,and list of posted Popular Electronics articles QST Radio & TV News Radio-Craft Radio-Electronics Short Wave Craft Wireless World About RF Cafe RF Cafe Homepage RF Cafe in Morse Code Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs Twitter LinkedIn Crosswords Engineering Humor Kirt's Cogitations Engineering Event Calendar RF Engineering Quizzes AN/MPN-14 Radar 5CCG Notable Quotes App Notes Calculators Education Magazines Software,T-Shirts,Coffee Mugs Articles - submitted by RF Cafe visitors Simulators Technical Writings RF Cafe Archives Test Notes Wireless System Designer RF Stencils for Visio Shapes for Word Search RF Cafe Sitemap Advertising Facebook RF Cafe Forums Thank you for visiting RF Cafe!

Mixed Signal PCB layout - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues. Original posts:

Amateur Radio | Antennas | Circuits & Components | Systems | Test & Measurement


Guest
Post subject: Mixed Signal PCB layout
Unread postPosted: Thu Jun 02, 2005 8:27 am

We make a pCB layout of a mixed signal board (High-speed digital and RF up to 400MHz). The board has 14 layers. The board is divided into 2 sections by a slot across the board. At he RF side we use only in 6 layers for the signals and grounds. My question is can we use the other layers as GND planes and stitch them with vias to the already used GND layers ? Is it recommended?


Top


Guest
Post subject:
Unread postPosted: Fri Jun 03, 2005 7:08 am

It is recommended. At 400MHz there is not alot of concern about stray RF, but the additional ground palnes will serve as a heatsink for the rest of the board. It is there, so you should use it.


Top


Another Guest
Post subject: ground planes
Unread postPosted: Wed Jun 08, 2005 11:23 am

Do remember that the vias which do the stitching together of the ground planes need to be spaced adequately close: well less than 1/10 of a wavelength at c in the medium (and that's not c in free space, but c/epsilon for the board material you're using. So if you're using a board material with a dielectric constant epsilon of 4, at 400 MHz one wavelength of a buried trace is 0.18 meters, so stitching vias should be absolutely no farther than 18 mm apart. I'd actually recommend much closer - say 2 mm - since you may have harmonics, or need a low-impedance connection.)

Good luck!


Top


Guest
Post subject:
Unread postPosted: Wed Jun 08, 2005 1:50 pm

Many thanks for your help!
I will do as you advised.

Thanks again!!! :-D



Posted  11/12/2012

RF Cafe Software

   Wireless System Designer - RF Cafe
Wireless System Designer

RF & EE Symbols Word
RF Stencils for Visio
Calculator Workbook
RF Workbench
Smith Chartâ„¢ for Visio
Smith Chartâ„¢ for Excel

About RF Cafe

Kirt Blattenberger - RF Cafe WebmasterCopyright
1996 - 2022
Webmaster:
Kirt Blattenberger,
 BSEE - KB3UON

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website:
 AirplanesAndRockets.com

Try Using SEARCH
to Find What You Need. 
There are 1,000s of Pages Indexed on RF Cafe !

height-line