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

  • From: Bert Simonovich <bertsimonovich@xxxxxxxxxx>
  • To: Mallikarjun K <malli.1729@xxxxxxxxx>
  • Date: Mon, 20 Oct 2014 21:57:31 -0400

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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