Same Impedance different trace width - Page 1
Forum section: electronics / general

author: jismal
author_rank: Contributor
timestamp: October 01, 2018, 07:10:48 am
content: Hello AllI am trying to achieve different trace width for same 50ohm impedance in the same layer in a 6 layer board. My current idea is to refer L1 traces having small thickness(5 mils 50 ohm) to L2 as reference,And for thicker traces (10mils 50ohm) to L3 by giving a keep-out in L2(GND) layer and give a GND polygon on L3 for referring L1 with L3. Is it a feasible solution. Any other ideas are welcome.Please note that thicker trace are for RF. And i have only very little experience with RF voodooL1______________________ ____ ____Top PlainL2>>>>>>>>>>>>>>>>>>>>> >>> GND PlainL3............................................ ............. .....SIG1 + GNDL4,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,SIG2L5<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<PWRL6__________________________________Bottom

author: xzswq21
author_rank: Frequent Contributor
timestamp: October 05, 2018, 09:39:51 pm
content: Quote from: jismal on October 01, 2018, 07:10:48 amHi, Say Hello to Indiaexactly. bcoz you should not have any impedance discontinuity. for example you have a SMA connector and you want to route the net to a IC's pin.you should cut the plane under the SMA connector pad (calculate how much you need , now the refrence plane is L3 or L4 or L5) then route a 5 mils line to the IC's pin (now the refrence plane is L2). if your frequency is very high pay attention to the component's pads as well.I have lot's of gerber files from big companies. if you are interested I can send youThanks

author: jismal
author_rank: Contributor
timestamp: October 08, 2018, 03:53:56 am
content: Thank you for the reply xzswq21and Namastey xzswq21My frequency would be 433 Mhz exact. From your reply i understand this idea works. And do i need to request special stackup from PCB vender specifying such condition, Or calculate by my own using Saturn PCB Design and proceed.It would be helpful if you share some Gerber.my mail Id would bejismal.jam@gmail.com

author: xzswq21
author_rank: Frequent Contributor
timestamp: November 23, 2018, 07:14:32 pm
content: Quote from: jismal on October 08, 2018, 03:53:56 amSorry for my late reply.it depends on you. you can send your sack-up to the PCB manufacture or you can use their stack-up! but all the impedance should be 50 OHM +/-10 % or 100 OHM +/-10 %instead of using Saturn please use Polar Instrument Si8000. Actually most of PCB manufactures use Polar Instruments (CITS series) to verify the impedance coupons.Plus you calculate the impedance of the vias in another software. Do you have any vias in high speed lines?

author: asmi
author_rank: Super Contributor
timestamp: November 23, 2018, 07:54:56 pm
content: Quote from: xzswq21 on November 23, 2018, 07:14:32 pmWe well as soon as you'll tell us where shall we get a ton of $$$ for a license

author: jismal
author_rank: Contributor
timestamp: November 26, 2018, 03:38:56 am
content: Ya I requested Custom Stack-up as you quoted. The project went fine. Its in production now. As you mentioned PCB Fab houses use Polar Instrument Si8000. It give the impedance as close as to the measured value. If you count USB 2.0 and EMMC 5.1 as HIGH speed , Yes then it have high speed signals.