Anshul, Don't mess with Vfixture and Rfixture. They are not going to make a difference in this situation. Unfortunately your attachment didn't make it through (these email servers are set up to strip attachments). Could you describe it in words what the discrepancy looks like (or send the attachment to me directly)? Thanks, Arpad =============================================== -----Original Message----- From: owner-ibis-users@server.eda.org [mailto:owner-ibis-users@server.eda.org] On Behalf Of Anshul Bansal Sent: Wednesday, October 15, 2008 8:47 AM To: ibis-users@server.eda.org Subject: [IBIS-Users] IBIS model for a slow slew rate output driver question Hello All, My name is Anshul Bansal and I am trying to create an IBIS model for an output driver that has the same drive strength but some config bits that can select different output slew rate settings. The fast setting for output driver has a slew rate in order of 5ns whereas the slow setting has a slew rate of 30-50ns. I have been able to successfully generate the IBIS model using the conventional method for rising and falling waveforms i.e. 50ohm termination resistor to ground and vcc_io. However when I try to run some co-relation simulations on the IBIS model and compare the results with the actual circuit, I can get very good co-relation (within 5-10% of actual circuit) for the fast setting of the output driver (waveform attached in fast.pdf). However the co-relation for slow setting of output driver is about 40-50% off as compared to actual circuit simulations (waveform attached in slow.pdf). I was wondering if there are other techniques that I should be using to model this slow setting for the output driver in the IBIS model, instead of the conventional settings like changing the Vfixture or Rfixture. Can anyone tell me how are such models captured by other engineers? Any response to these questions are highly welcome. Thanks, Anshul -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -------------------------------------------------------------------- |For help or to subscribe/unsubscribe, e-mail majordomo@eda-stds.org |with the appropriate command message(s) in the body: | | help | subscribe ibis <optional e-mail address, if different> | subscribe ibis-users <optional e-mail address, if different> | unsubscribe ibis <optional e-mail address, if different> | unsubscribe ibis-users <optional e-mail address, if different> | |or e-mail a request to ibis-request@eda-stds.org. | |IBIS reflector archives exist under: | | http://www.eda-stds.org/pub/ibis/email_archive/ Recent | http://www.eda-stds.org/pub/ibis/users_archive/ Recent | http://www.eda-stds.org/pub/ibis/email/ E-mail since 1993 -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -------------------------------------------------------------------- |For help or to subscribe/unsubscribe, e-mail majordomo@eda-stds.org |with the appropriate command message(s) in the body: | | help | subscribe ibis <optional e-mail address, if different> | subscribe ibis-users <optional e-mail address, if different> | unsubscribe ibis <optional e-mail address, if different> | unsubscribe ibis-users <optional e-mail address, if different> | |or e-mail a request to ibis-request@eda-stds.org. | |IBIS reflector archives exist under: | | http://www.eda-stds.org/pub/ibis/email_archive/ Recent | http://www.eda-stds.org/pub/ibis/users_archive/ Recent | http://www.eda-stds.org/pub/ibis/email/ E-mail since 1993Received on Wed Oct 15 08:02:39 2008
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