Kiran, The V(t) tables under different load conditions are all supposed to be used to generate a single model, so no choice is required. The nominal model is a pullup transistor, a pulldown transistor, a power clamp, a ground clamp, and capacitance to ground. The V(t) curves make it possible for the simulation tool to estimate the switching characteristics of the two transistors. Two V(t) curves at different loading conditions are required to compute the two transistor characteristics. If only one curve is supplied then the tool must assume that the switching of the two transistors is complimentary. If more than two V(t) curves are supplied the system is over determined. Most tools ignore the additional curves. Ideally a least-squares fitting should be used to generate a model that best matches all supplied V(t) values. I don't think any tools do that today. Christopher E. Reid Chief Scientist and Founder Pressando SI 9315 SW Lake Street Tigard, OR 97223-6034 503-869-6703 (cell) 503-624-8159 (home) ----- Original Message ----- From: seshadri.kirankumar@wipro.com To: ibis-users@server.eda.org ; ibis@server.eda.org Sent: Wednesday, May 03, 2006 6:46 AM Subject: [IBIS-Users] Question regarding V-T data of IBIS model Hi Experts, I have a doubt on IBIS modeling regarding to V-T data using a Signal Integrity tool. Suppose if IBIS model contains V-T data generated for different R_fixtures . how SI engineer is able to make the tool to use required R_fixture data from all V-T tables? As an example if I am generating V-T data(2 Risings and 2 Fallings) against 2 Rloads i.e RLOAD1 and RLOAD2 both are less than 100 Ohms, then s2ibis3 will put V-T will be in the below following order based on assumption RLOAD1 > RLOAD2 Rising connected VSS using RLOAD1 Rising connected VDDS using RLOAD1 Rising connected VSS using RLOAD2 Rising connected VDSS using RLOAD2 Falling connected VSS using RLOAD1 Falling connected VDDS using RLOAD1 Falling connected VSS using RLOAD2 Falling connected VDSS using RLOAD2 So how a person using SI tool will chose the required V-T table data based on RLOAD1 and RLOAD2 ? or will these be taken care automatically by the tool? Thanks for providing information on this 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 ----------------------------------------------------------------- |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 Wed May 3 08:53:03 2006
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