All, Thanks for the information and replies. The buffer is using a feedback which changes the drivestrengths. Currently we are going to chop the ringing portion of the IBIS V-T data which looks the safer option and go ahead. Thanks again vinayak Muranyi, Arpad wrote: >Andy, > >You are absolutely correct, there are different >types of feedbacks, and I should have defined >which one I was referring to in my posting... > >I was thinking of one that adjusts the drive >strength real time as the buffer is switching. >Legacy IBIS can't do that. (Although one could >model these too using the *-AMS extensions of >IBIS). > >On the other hand, buffers which adjust their >own drive strength only once and a while to >compensate for temperature variations, for >example, can be modeled in IBIS as if they were >normal buffers, because they don't change skins >while driving signals onto the bus. You may >need the [Model Selector] keyword to make a >few different driver models available for the >various strengths, but that's all. > >Arpad >------------------------------------------------ > >-----Original Message----- >From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of Andrew Ingraham >Sent: Wednesday, January 04, 2006 9:31 AM >To: ibis-users@eda.org; ibis@eda.org >Subject: [IBIS] Re: hspice vs IBIS model correlation at different capacitive loads > > > >>I think he is saying that the oscillations happen >>because of the feedback in the buffer is trying to >>settle to a steady state condition. >> >>If so, legacy IBIS can not model your buffer, since >>there are no provisions for describing feedback. >> >> > >Yes. > >Although it depends on the feedback. > >Linear negative feedback, such as used on op-amps to reduce output >impedance, should work OK, I think. It's probably also possible that some >forms of feedback to reduce variations in drive strength (for example), >ought to be somewhat compatible with conventional IBIS. But things like >positive feedback to give hysteresis, don't play well in IBIS. > >Regards, >Andy > >----------------------------------------------------------------- >|For help or to subscribe/unsubscribe, email majordomo@eda.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 email a request to ibis-request@eda.org. >| >|IBIS reflector archives exist under: >| >| http://www.eda.org/pub/ibis/email_archive/ Recent >| http://www.eda.org/pub/ibis/users_archive/ Recent >| http://www.eda.org/pub/ibis/email/ E-mail since 1993 > > ----------------------------------------------------------------- |For help or to subscribe/unsubscribe, email majordomo@eda.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 email a request to ibis-request@eda.org. | |IBIS reflector archives exist under: | | http://www.eda.org/pub/ibis/email_archive/ Recent | http://www.eda.org/pub/ibis/users_archive/ Recent | http://www.eda.org/pub/ibis/email/ E-mail since 1993Received on Thu Jan 5 06:55:19 2006
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