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SYiwe's avatar
SYiwe
Icon for Occasional Contributor rankOccasional Contributor
6 years ago

How can I convert "ps" to "mil" in EMIF layout guidelines?

Some design guidelines in EMIF user guide use "ps" as unit, as you can see in the following screenshot. But in the pcb design, I must check the route lines by mils or millimeter, how can I convert "...
ak6dn's avatar
ak6dn
Icon for Regular Contributor rankRegular Contributor
6 years ago

In my above answer I use Tpd to refer to the propagation delay factor for a given trace, and it would be specified in the units of ps/mil (or ps/in, or ps/cm, or some length/time unit).

So if you then need to do a, for example 100ps delay on a trace with a Tpd factor of 170ps/inch (a quite common PCB velocity factor) the trace would be ~590 mils in length.

Most PCB velocity factors (for standard epoxy fiberglass materials) in the range of 100-200ps/inch. More exotic dielectrics (like teflon, etc) can be quite different.

I find the Saturn PCB toolkit (free download at http://www.saturnpcb.com/pcb_toolkit/) to be quite helpful for examining PCB characteristics.

  • SYiwe's avatar
    SYiwe
    Icon for Occasional Contributor rankOccasional Contributor
    6 years ago

    Thank you very much for your answer, that is really helpful.