PADS for impedance calculation ?

[san2004]

pads impedance mentor

Hi frnds,

Can we use MENTOR GRAPHICS PADS LAYOUT for characteristics impedance calculations of the traces ? In high speed rules alongwith parameters like capacitance, delays we can assign min & max value of impedance but can we use it for calculation of impedance to decide trace width & clerance of critical signals like DDR2 ?
Thanks in advance,

Bye...

 

[otherguy]

layout impedance

There is no impedance calculator included with Pads Layout. We use the stackup calculator in Hyperlynx for our impedance calculations. There are many other free calculators available. Off the top of my head, I can think of Polar and z-calc but I never liked these.

 

[edaedaeda]

pads layout impedance

It is a good idea to contact your board manufacturer in regards to impedance calculations. They will be happy to give you a complete stackup.
But in the meantime.... To get the general ballpark number there are several calculators you can use. Many online versions can be found with a simple internet search. Personally, use Polar. Very nice tool. But make sure you are using a newer version 8 or better.

I am guessing that your reference to impedance in Mentor PADS is by viewing the layer stack manager. If so, I would NOT use this bas base your impedance on.

Just in case I am including the Faraday DDR II doc for you.

Hope this helps.