[SI-LIST] Re: Transmission line impedance is related to signal switching frequency ?
- From: "Tom Dagostino" <tom@xxxxxxxxxxxxx>
- To: <sguzek@xxxxxxxxx>, "Si-List" <si-list@xxxxxxxxxxxxx>
- Date: Tue, 25 Jan 2005 12:24:08 -0800
What your PCB manufacture is likely telling is they don't know the Er of
their board materials at that frequency. Without knowing that they cannot
keep to your spec.
Tom Dagostino
Teraspeed Consulting Group LLC
503-430-1065
tom@xxxxxxxxxxxxx
www.teraspeed.com
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On
Behalf Of Slawek Guzek
Sent: Tuesday, January 25, 2005 12:12 PM
To: Si-List
Subject: [SI-LIST] Re: Transmission line impedance is related to signal
switching frequency ?
Dear Peter,
I guess probably in your stackup design 100 ohms tracks are
very narrow and very sensitive to tolerance.
You can try to use thicker dielectric, at least between
ground plane and layer with controlled impedance tracks,
to make them wider and easier to control.
Regards,
Slawek
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Pang Ning
> Sent: Tuesday, January 25, 2005 10:12 AM
> To: si-list@xxxxxxxxxxxxx
> Cc: peter_pang@xxxxxxxxxxxxxxxx
> Subject: [SI-LIST] Transmission line impedance is related to signal
> switching frequency ?
>
>
> Dear all,
> I have a confusion about the PCB transmission line impedance. As I knew
before, the transmission line impedance depends
> on the square root of L/C. That is to say, signal switching frequency will
not impact transimission line impedance.
>
> But just now one famous PCB manufacturer informed me that they can't
control differential pair impedance to 100ohm at the
> 1.25GHz frequency. I felt confused about the frequency will impact
transmission line impedance. Does anybody can give me
> some idea about this question? Thanks a lot!
>
> Best Regards,
> Peter Pang
>
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