[SI-LIST] Re: Point to point simulation results

  • From: Mallikarjun K <malli.1729@xxxxxxxxx>
  • To: preetesh rathod <preeteshrathod@xxxxxxxxxxx>, "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
  • Date: Wed, 22 Oct 2014 19:56:38 +0530

The receiver IO model i selected is Without ODT.
I will try with single Pulse.....

On Wed, Oct 22, 2014 at 5:39 PM, preetesh rathod <preeteshrathod@xxxxxxxxxxx
> wrote:

> Hello
>          You haven't mentioned anything about end termination (ODT) if
> you using it. In your case it seems impedance mismatch at both ends. So
> your single pulse reflections may not die out in single cycle which can
> create such type of results at different trace lengths. I suggest you to
> simulate with single edge which will help you to understand what is going
> on in more detail in terms of reflections.
>
> Regards
> Preetesh Rathod
>
>
>   On Tuesday, 21 October 2014 7:30 AM, Bert Simonovich <
> bertsimonovich@xxxxxxxxxx> wrote:
>
>
> This looks like a case of driver impedance mismatch to the transmission
> line. The driver likely has a lower impedance than the transmission line.
> Try increasing the 0 ohm resistor to a value equal t-line impedance minus
> the driver impedance. Eg. if the driver impedance is 15 ohms, and the
> t-line is 50 ohms, then the resistor should be 35 ohms.
>
> Sent from my iPad
>
> > On Oct 20, 2014, at 8:41 PM, Mallikarjun K <malli.1729@xxxxxxxxx> wrote:
> >
> > Hi,
> > I am trying to simulate a topology.
> > it consists of driver --> 0 ohm resistor --> MS line (length varied from
> > 1000 mils to 10000 mils) ---> DDR2 dq 533 io(receiver).
> >
> > I am just simulating to findout how much can be the maximum length,
> before
> > signal degrades badly.
> >
> > As i am increasing the length, i am seeing more degradation at the Driver
> > than at the receiver. there is degradation at the receiver , but it is
> OK.
> >
> > I have uploaded 3 files 1000mils,4800mils and 10000mils
> > @ 10000mils there is delay between input and output but still output
> > quality and input quality are good compared to 4800 mils case.
> >
> > why is this? 10000mils case should have more degradation
> >
> > http://s3.postimg.org/q6wi1e283/ddr2_io_0000_dq_533_MS3_1000.png
> >
> > http://s2.postimg.org/4qw22kazt/ddr2_io_0000_dq_533_MS3_4800.png
> >
> > http://s27.postimg.org/o988g61zn/ddr2_io_0000_dq_533_MS3_10000.png
> >
> >
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