Hello everybody Thank you very much for your feedback. In my open drain ibis model, I have extracted Rise and fall wave by TX level simulation of buffer (spice) connecting a load resistance value equal to 20K between open drain pad and power. In this case I have considered the real delay between transient of input signal and output. Now if I consider the same input signal (by which I have extracted Rise and Fall tables) for ibis model and the same resistance value (20k), I should have the same behaviour between Ibis and spice buffer. Thanks and best regards. Roberto Izzi Dimitry Eisenshtat wrote: > Hi all, > Mei Yee, if you see the buffer to be modeled as box with some > interface (lets speak for example about one directional buffer which > has only transmitter, so the interface in simplest case will be > data_from_core, enable, pad) - you of course expected from IBIS > representation the same (in ideal case) behavioral as the > transistor-level simulation with spice, in other words, no delay is > expected between both transient responses. But it is the artificial > situation, in real life you are looking from board level and you can > not synchronize your simulation with signal inside the core aren't > you? How you can define for example WHEN the input signal starts the > transition - it dependent on unknown digital stage number the signal > is walking on before the buffer data_from_core input, isn't it ? As i > understand, the delay from enable to pad is meaningless, because > actually you can not define absolute time in board-level scope, only > the transition itself is important. Another question is - why the > delay comes to be, but for example the answer may be the time > windowing of V/T tables (I mean the model maker probably shifts the > transients response table in order to make the time window smaller, > for example). > > I have to say, I'm circuit designer and I has produced a lot of IBIS > models, but has actually no knowledge about using of these models on > board level, so I really like to know if I have a mistake. Aubrey, did > you mean the same things? > > Regards, > Dmitry > > NG,MEI-YEE wrote: > >> Hi everybody, >> I would like to say that I experienced the same phenomenon as Roberto, >> with the IBIS waveform delayed compared to the transistor level >> simulation. Aubrey, what do you mean by IBIS model doesn't contain >> buffer delay? How does that explain IBIS model being delayed in the >> output response? >> >> Appreciate any feedback. Thank you. >> >> Best regards, >> Mei Yee >> >> -----Original Message----- >> From: owner-ibis-users@server.eda.org >> [mailto:owner-ibis-users@server.eda.org] On Behalf Of >> Aubrey_Sparkman@dell.com >> Sent: Friday, January 12, 2007 12:15 AM >> To: roberto.izzi@st.com; ibis@server.eda-stds.org; >> ibis-users@server.eda.org >> Subject: RE: [IBIS-Users] Ibis open drain strange behaviour >> >> Is your only concern the time delay? IBIS and Spice aren't always >> aligned in time since IBIS doesn't contain the buffer delay. >> >> >> Aubrey Sparkman Enterprise Engineering Signal Integrity Team >> Dell, Inc. Aubrey_Sparkman@Dell.com (512) 723-3592 >> >> The Greatest Pleasure in Life is Doing what People say can't be done... >> >> -----Original Message----- >> From: owner-ibis-users@server.eda.org >> [mailto:owner-ibis-users@server.eda.org] On Behalf Of Roberto IZZI >> Sent: Thursday, January 11, 2007 10:08 AM >> To: ibis@server.eda-stds.org; ibis-users@server.eda.org >> Subject: [IBIS-Users] Ibis open drain strange behaviour >> >> Hello everybody >> >> I 'd like to have some information about a strange behaviour of Open >> drain buffer Ibis model. >> I have noticed a mismatch between Transistor level and Ibis model >> voltage output during a transient analysis, considering the same buffer. >> In fact in presence of the same input voltage wave and for a high value >> of load resistance(for example 20Kohm)connected to power, we can observe >> a delay between TL output and Ibis output. In the Ibis file, for Open >> drain, Rise and fall waves tables have been >> extracted considering the same resistance connected to Power (20Kohm). >> What is the cause of this strange behaviour? >> >> Thanks and best regards >> >> Roberto Izzi >> >> >> -- >> This message has been scanned for viruses and dangerous content by >> MailScanner, and is believed to be clean. >> > > > =========================================================================================== > > The privileged confidential information contained in this email is > intended for use only by the addressees as indicated by the original > sender of this email. If you are not the addressee indicated in this > email or are not responsible for delivery of the email to such a > person, please kindly reply to the sender indicating this fact and > delete all copies of it from your computer and network server > immediately. Your cooperation is highly appreciated. It is advised > that any unauthorized use of confidential information of Winbond is > strictly prohibited; and any information in this email irrelevant to > the official business of Winbond shall be deemed as neither given nor > endorsed by Winbond. > -- 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 Fri Jan 12 00:16:09 2007
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