[SI-LIST] Re: Slew Rate Calculation
- From: "Bingipur, Arjun" <arjun.bingipur@xxxxxxxxxx>
- To: "tao xu" <helen.tao.xu@xxxxxxxxx>
- Date: Thu, 30 Nov 2006 18:22:08 +0530
From the discussions, I gather that I've two options.
One - changing the termination value
Two - adding a capacitor b/w the lines
The second option suits well I suppose. At least I'll be confident of
meeting the SI issues.
The 6V/ns was the differential slew rate.
Regards,
Arjun Bingipur
-----Original Message-----
From: tao xu [mailto:helen.tao.xu@xxxxxxxxx]=0D
Sent: Thursday, November 30, 2006 3:08 PM
To: Bingipur, Arjun
Cc: si-list@xxxxxxxxxxxxx
Subject: Re: [SI-LIST] Re: Slew Rate Calculation
In that case, you can change value of termination R. But before that,
please make sure that there's no missetting in your simulation as
benny has mentioned days ago.
BTW, is 6V/ns single ended slew rate or differential slew rate? if it
is single ended slew rate. highly recommend to recheck the model in
your top.
On 11/30/06, Bingipur, Arjun <arjun.bingipur@xxxxxxxxxx> wrote:
>
> I'm using a discrete implementation of the memory.
>
> Regards,
> Arjun Bingipur
>
> -----Original Message-----
> From: tao xu [mailto:helen.tao.xu@xxxxxxxxx]
> Sent: Thursday, November 30, 2006 2:38 PM
> To: tom@xxxxxxxxxxxxx
> Cc: Bingipur, Arjun; si-list@xxxxxxxxxxxxx; bennyzhi@xxxxxxxxx
> Subject: Re: [SI-LIST] Re: Slew Rate Calculation
>
> you had to define your usage enviroment at first to see if you can
> change termination.
>
> If your board is embedded structure, you have chance to change the
> termination R value. But if you use DIMM, the value of differential
> termination R is already set. you can not vary it.
>
> On 11/30/06, Tom Dagostino <tom@xxxxxxxxxxxxx> wrote:
> > I can think of a few:
> >
> > Unmatched termination -> SI issues
> > Stronger load -> lower voltage swing
> > More current -> higher power dissipation
> > More current -> more power supply noise
> > Faster slew rate -> more radiation
> > Faster slew rate -> more crosstalk
> >
> > Tom Dagostino
> > Teraspeed(R) Labs
> > 13610 SW Harness Lane
> > Beaverton, OR 97008
> > 503-430-1065
> > tom@xxxxxxxxxxxxx=3D20
> > www.teraspeed.com=3D20
> >
> > Teraspeed Consulting Group LLC
> > 121 North River Drive
> > Narragansett, RI 02882
> > 401-284-1827
> >
> > -----Original Message-----
> > From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx] =3D
> > On
> > Behalf Of Bingipur, Arjun
> > Sent: Thursday, November 30, 2006 12:35 AM
> > To: si-list@xxxxxxxxxxxxx
> > Cc: bennyzhi@xxxxxxxxx
> > Subject: [SI-LIST] Re: Slew Rate Calculation
> >
> >
> >
> > Sorry, a typo. It is DDR2.
> >
> > Micron recommends a differential termination in the range of 100-120
=3D
> > ohms
> > between the clock pairs, which will yield a high slew rate. Probably
=3D
> > because
> > of the small load. But, my optimal slew rate is achieved by tweaking
> the
> > termination to around 33-35 ohms in the simulation. Does this in any
> way
> > influence the performance?
> >
> > Regards,
> > Arjun Bingipur
> >
> > -----Original Message-----
> > From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]
> > On Behalf Of Benny Yan
> > Sent: Monday, November 27, 2006 8:30 AM
> > To: Bingipur, Arjun
> > Cc: si-list@xxxxxxxxxxxxx
> > Subject: [SI-LIST] Re: Slew Rate Calculation
> >
> > Should it be DDR2?
> > It seems that the loading is too small, have you checked the model
you
> =3D
> > used?
> > like package, C_comp...
> >
> > On 11/25/06, Bingipur, Arjun <arjun.bingipur@xxxxxxxxxx> wrote:
> > >
> > >
> > > Hi,
> > >
> > > I'm doing a static timing analysis for determining the slew rate
for
> > the
> > > differential clock signals of a DDR. When I do a slew rate
> derating=3D20
> > > calculation on the eye diagram, I end up with values of around
6V/ns
> > and
> > > I 'm unable to consider this value to compare with the
> address/command =3D
> >
> > > derating values to arrive at the correct setup and hold time
values
> in =3D
> >
> > > the data sheet.
> > >
> > > The topology is such that a controller is driving a single DDR
with
> a=3D20
> > > differential termination of 120 ohm connected close to the
receiver
> > IC.
> > > Am I missing something here?
> > >
> > > Regards,
> > > Arjun Bingipur
> > >
> > >
> > >
> > >
> >
>
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