[SI-LIST] Re: Point to point simulation results
- From: "Chen, Sherman" <sherman.chen@xxxxxxx>
- To: "bertsimonovich@xxxxxxxxxx" <bertsimonovich@xxxxxxxxxx>, Mallikarjun K <malli.1729@xxxxxxxxx>
- Date: Sun, 9 Nov 2014 04:07:09 +0000
Hi,
The 4800mil waveform shows both source and load ends are mismatch. The reason
why 1000mil and 10kmil give a less distorted signal is bcs at these lengths the
impd seen from the source is close to Zload - you will see it clearly if
drawing a Smith chart.
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Bert Simonovich
Sent: Tuesday, October 21, 2014 9:58 AM
To: Mallikarjun K
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Point to point simulation results
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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