Re: Series Termination
- From: John Larkin <jjlarkin@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Sun, 22 Feb 2009 18:17:26 -0800
On Sat, 21 Feb 2009 09:48:11 -0800 (PST), heilig.brian@xxxxxxxxx
wrote:
I am trying to understand series termination for a board I'm designing
with a Cyclone II FPGA. The Cyclone II has internal series termination
resistors making it easier for me. These resistors are typical 50 ohms
(25 in some cases). I assume the traces on my board must also be a 50
ohm transmission line so I plug some numbers into a microstrip trace
impedance calculator (at http://www.chemandy.com/calculators/microstrip-transmission-line-calculator-hartley27.htm
using specs for the board from http://www.expresspcb.com/ExpressPCBHtm/SpecsStandard.htm)
and it says I need a trace that is 1.5 mm wide. That trace is too
wide...it'll cover three pins! I think I must be missing something
because when I look at a PCB I don't see traces this wide for data.
Thanks for your help,
Brian
What's the layer stackup like?
Appcad is a nice impedance calculator.
John
.
- Follow-Ups:
- Re: Series Termination
- From: heilig . brian
- Re: Series Termination
- References:
- Series Termination
- From: heilig . brian
- Series Termination
- Prev by Date: Re: Learning PIC - where to start?
- Next by Date: skiing terminology
- Previous by thread: Re: Series Termination
- Next by thread: Re: Series Termination
- Index(es):
Relevant Pages
|
