I can think of a few: Unmatched termination -> SI issues Stronger load -> lower voltage swing More current -> higher power dissipation More current -> more power supply noise Faster slew rate -> more radiation Faster slew rate -> more crosstalk Tom Dagostino Teraspeed(R) Labs 13610 SW Harness Lane Beaverton, OR 97008 503-430-1065 tom@xxxxxxxxxxxxx=20 www.teraspeed.com=20 Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 401-284-1827 -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] = On Behalf Of Bingipur, Arjun Sent: Thursday, November 30, 2006 12:35 AM To: si-list@xxxxxxxxxxxxx Cc: bennyzhi@xxxxxxxxx Subject: [SI-LIST] Re: Slew Rate Calculation Sorry, a typo. It is DDR2. Micron recommends a differential termination in the range of 100-120 = ohms between the clock pairs, which will yield a high slew rate. Probably = because of the small load. But, my optimal slew rate is achieved by tweaking the termination to around 33-35 ohms in the simulation. Does this in any way influence the performance? Regards, Arjun Bingipur -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Benny Yan Sent: Monday, November 27, 2006 8:30 AM To: Bingipur, Arjun Cc: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Slew Rate Calculation Should it be DDR2? It seems that the loading is too small, have you checked the model you = used? like package, C_comp... On 11/25/06, Bingipur, Arjun <arjun.bingipur@xxxxxxxxxx> wrote: > > > Hi, > > I'm doing a static timing analysis for determining the slew rate for the > differential clock signals of a DDR. When I do a slew rate derating=20 > calculation on the eye diagram, I end up with values of around 6V/ns and > I 'm unable to consider this value to compare with the address/command = > derating values to arrive at the correct setup and hold time values in = > the data sheet. > > The topology is such that a controller is driving a single DDR with a=20 > differential termination of 120 ohm connected close to the receiver IC. > Am I missing something here? > > Regards, > Arjun Bingipur > > > > ************************************************************************ ***=3D3D > ************* > > Note: If the reader of this message is not the intended recipient, or an=3D3D > employee or agent responsible for delivering this message to the intended=3D3D > recipient, you are hereby notified that any dissemination, distribution > or=3D3D > copying of this communication is strictly prohibited. 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