[SI-LIST] Re: package model of SSD
- From: "Tom Dagostino" <tom@xxxxxxxxxxxxxxxxx>
- To: "'Han, Guobing'" <han.guobing@xxxxxxxxx>
- Date: Tue, 3 Feb 2015 11:02:38 -0800
Robin
It all depends on what signals you have access to. And what kinds of
reflections are in your system. You can easily get NEXT, shoot the TDR
pulse into one net and measure the NEXT on the others. To get FEXT, well,
if the system has a good termination at the receiver it will be impossible
unless you have access at the receiver. If you can shut off the termination
at the receiver you can measure you can measure the FEXT for a signal
referenced to the receiver. Turn off the termination, TDR the net and
measure the other net. The first data coming out will be the NEXT and when
the TDR reflection comes back you will also see the FEXT referenced to the
receiver end. You will get some indication of FEXT but the risetime of the
TDR edge will already be degraded so you won't have a perfect answer.
Tom Dagostino
Teraspeed Labs
9999 SW Wilshire Street
Suite 102
Portland, OR 97225
tom@xxxxxxxxxxxxxxxxx
www.teraspeedlabs.com <http://www.teraspeedlabs.com/>
971-279-5325 office
503-430-1065 cell
From: Han, Guobing [mailto:han.guobing@xxxxxxxxx]
Sent: Monday, February 02, 2015 10:01 PM
To: tom@xxxxxxxxxxxxxxxxx
Cc: shermanchen001@xxxxxxxxx; SI LIST
Subject: Re: [SI-LIST] Re: package model of SSD
Sherman and Tom,
I think It's a very practical thought.
For serial link, it should works.
But, how about the parellel links considering the mutual couplings? Any
suggestions?
Thanks,
Robin
2015-02-02 15:36 GMT+08:00 Tom Dagostino <tom@xxxxxxxxxxxxxxxxx>:
Sherman
That should work. Mindful that you are not simulating crosstalk or losses
though. If the SSD looks like a FR4 pcb then you can add about 0.02 as Dk.
If you know the material is not standard run of the mill FR4 then look up
the Dk on the manufacturer's web page.
You can also model crosstalk with TDR to some degree. You likely have
access to the other pins at the input of the SSD to NEXT is easy. For FEXT
you will need access to the receiver/drivers in the SSD.
Keep your measurement path's return as close as possible to the signal, you
don't want large inductive discontinuities caused by the loop of the probe.
Having a fixture with proper connectors on it will help immensely.
Good luck
Tom Dagostino
Teraspeed Labs
9999 SW Wilshire Street
Suite 102
Portland, OR 97225
tom@xxxxxxxxxxxxxxxxx
www.teraspeedlabs.com
971-279-5325 office
503-430-1065 cell
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Sherman Chen
Sent: Sunday, February 01, 2015 11:20 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: package model of SSD
On Mon, Feb 2, 2015 at 1:46 AM, Sherman Chen <shermanchen001@xxxxxxxxx>
wrote:
> Hi,
>
> I need to run channel simulation but lack the model of SSD. If we have
> to figure the package model by ourselves, I figure the following
> method might
> work:
> 1. Do accurate TDR on SSD to get the impd profile of the SSD package.
> 2. Construct the pkg model in ADS to emulate the measured TDR profile.
> I first tried using L, C components to emulate the TDR profile but
> this takes more time than using tline. Then I realized it should be
> the same using multiple segments of tlines w/ each having different Z0
> and delay instead of L or C.
> 3. Use the constructed model for channel simulation.
>
> I'd appreciate if you point out the probelm of above method in
> emulating a pkg model. Any comment will be highly welcome, too.
>
> Regards,
>
> Sherman
>
>
>
>
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Thanks,
- Robin (Han, Guobing)
TEL: 86-21-61094805
MSN: han_guobing@xxxxxxxxxxx
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