Kiran, I understand that you can't send us your circuit files, don't worry about that... It sounds like your SPICE model may have flip/flop-s in it, and the first transition gives you an incorrect voltage because SPICE doesn't initialize all nodes correctly, and consequently there may be some internal contentions inside the circuit. After the first transition the f/f-s are in a "known state" and from there on your waveforms are correct. This may only show up on one side of the differential output because they are in a complementary state, and by chance it may be possible that the f/f for one output happened to start in the correct state, but the f/f for the other output didn't (since it had to be in the opposite state). As Lynne wrote, there is no requirement that you take the first transition of this simulation for the IBIS model data. To the contrary, for these and similar reasons we usually prefer to take the data from later transitions when the buffer is more in the "steady state" conditions. I hope this will help you in your work. Arpad ------------------------------------------------------------ ________________________________ From: seshadri.kirankumar@wipro.com [mailto:seshadri.kirankumar@wipro.com] Sent: Tuesday, February 07, 2006 4:23 AM To: Muranyi, Arpad; ibis-users@eda.org; ibis@eda.org Subject: RE: [IBIS-Users] issue in VT extraction Arpad , I am not doing simulation on IBIS file but in the procedure to generate IBIS model of VT data i.e Rising and Falling connecting to VSS that means the plot which you saw was spice3 simulation result done on the spice netlist using 2 decks one for Rising and one for Falling. As I don't have permissions to send this decks and inputs for generation of IBIS I could not send across. Hope this clear your point spice3 does not have feature to simulate IBIS model. Best Regards Kiran Kumar ________________________________ From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Muranyi, Arpad Sent: Monday, February 06, 2006 10:00 PM To: ibis-users@eda.org; ibis@eda.org Subject: RE: [IBIS-Users] issue in VT extraction Kiran, I am not sure whether you answered my question correctly. I was wondering what simulator did you use to simulate the IBIS model, not what simulator you used to generate the Vt data for the IBIS model. Does spice3 have an IBIS buffer element? Arpad =============================================== ________________________________ From: seshadri.kirankumar@wipro.com [mailto:seshadri.kirankumar@wipro.com] Sent: Thursday, February 02, 2006 8:21 PM To: Muranyi, Arpad; ibis-users@eda.org; ibis@eda.org Subject: RE: [IBIS-Users] issue in VT extraction Arpad, This data for plot is generated using spice3 Best Regards Kiran Kumar ________________________________ From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Muranyi, Arpad Sent: Thursday, February 02, 2006 10:06 PM To: ibis-users@eda.org; ibis@eda.org Subject: RE: [IBIS-Users] issue in VT extraction Kiran, Which simulator did you use when you made this waveform? Arpad ================================ ________________________________ From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of seshadri.kirankumar@wipro.com Sent: Thursday, February 02, 2006 3:19 AM To: ibis-users@eda.org; ibis@eda.org Subject: [IBIS-Users] issue in VT extraction Hi IBIS Experts, I have an query in IBIS modeling about extracting VT data, I am generating model for one buffer which is having its output swing from +0.21V to -0.21V, But as you see in the Plot for Rising (if the i/p pulse is Rising ) then it is giving proper switching (Red coloured) But in Falling (if the i/p pulse is falling) then for 1 st pulse it is not going down and reaching to -0.21V even I tried giving very low frequency i/p signal(Green coloured). Here my doubt is why IBIS takes first 1/4 th of Pulseperiod of i/p signal, is there any reason in that? If there is no any constraint on this as I am seeing the good performance in second pulse onwards I can do a X-axis shift (Time shift) of the second Falling Pulse. I wanted this clarification because I am not aware of internal architecture which causing this problem in the netlist(input) which I am using for generation. Thanks in Advance Best Regards Kiran Kumar The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately and destroy all copies of this message and any attachments. WARNING: Computer viruses can be transmitted via email. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email. www.wipro.com The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately and destroy all copies of this message and any attachments. WARNING: Computer viruses can be transmitted via email. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email. www.wipro.com The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately and destroy all copies of this message and any attachments. WARNING: Computer viruses can be transmitted via email. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email. www.wipro.com ----------------------------------------------------------------- |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 Tue Feb 7 09:32:03 2006
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