stimulus doubt - address simulation for DDR2.

Dear ExpertsI have done the address simulation for DDR2.When I give a stimulus using 200MHz oscillator waveform with 50% dutycycle, I get a good waveform.If I give a stimulus using PRBS pattern, I get a waveform with moreringing.Is it because of the topology error or ibis model?I checked with another ibis model also. But the observations are same.I am using HyperLynx 8.2.1Please assist me to correct the waveform.-- Best Regards,Balamanikandan.K
kbmanick 7 years 6 months 10 days

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Answered byvladimir_dmitriev-zdorov 7 years 6 months 10 days
Hi Balamanikandan,When you apply oscillator input (periodic), the spectrum of your signal contains only odd harmonics of the base frequency.When you apply PRBS of a high order, the spectrum is richer, with many additional low and mid frequency components. Some of them cause resonances in your channel, visible as ringing.Vladimir 
Answered byweirsi 7 years 6 months 10 days
What do you do to switch patterns?Steve.On 5/29/2013 9:25 PM, Balamanikandan K wrote:> Dear Experts>> I have done the address simulation for DDR2.>> When I give a stimulus using 200MHz oscillator waveform with 50% duty> cycle, I get a good waveform.>> If I give a stimulus using PRBS pattern, I get a waveform with more> ringing.>> Is it because of the topology error or ibis model?>> I checked with another ibis model also. But the observations are same.>> I am using HyperLynx 8.2.1>> Please assist me to correct the waveform.>-- Steve WeirIPBLOX, LLC1580 Grand Point WayMS 34689Reno, NV  89523-9998www.ipblox.com(775) 299-4236 Business(866) 675-4630 Toll-free(707) 780-1951 FaxAll contents Copyright (c)2013 IPBLOX, LLC.  All Rights Reserved.This e-mail may contain confidential material.If you are not the intended recipient, please destroy all recordsand notify the sender.