Hello Shilpa-- This is a fundamental property of any bus that does not have the driver, T-line, and receiver perfectly matched (which is pretty much any bus) - there are reflections. In fact, DDR3 has fast enough edges that you will see a difference in the receiver waveform at the pin versus the waveform at the die. The shape of the waveform is determined by how those reflections line up, and will look the best at the endpoint of the bus (the die). We walk through an example of propagating reflections and the resulting waveform shapes in our Transmission Lines, Reflections, and Terminations Webinar available at: http://www.mentor.com/products/pcb-system-design/series/si-basics-series Because of reflections, it is important to note that the waveform viewed at the driver (in measurement or simulation) isn't the same waveform that is "sent out" onto the bus. That is why timing is measured from the driver into a standard test load, and should not be measured from driver waveform to receiver waveform. This topic is discussed in the Timing Webinar at the link above. --Pat BTW, you may also be interested in our webinar on designing DDRx busses: http://www.mentor.com/products/pcb-system-design/multimedia/ddrx-design-webinar/ -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Shilpa Patil Sent: Sunday, September 16, 2012 11:46 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Signal at the driver Hi SI Experts, I have been carrying out the analysis for DDR3 memory. My query is that at the driver end I can see a signal with a dip and shorter peak-peak the signal is not a pulse even though I have given a pulse, but at the receiver the signal is good. So why is the signal at the driver so not a proper pulse? Regards, Shilpa P ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu