Hi Tom, Thanks for clarifying this. One more question, what is the difference between the manufacturer's suggested pullup load resistor used in V-T values extraction and the Rref value specified? In my case, the suggested pullup is 1.5KOhm, so I only need a 50 Ohm V-T table and my Rref = 1.5Kohm? Thank you very much. Best regards, Mei Yee SID, Avago Technologies (Malaysia) Tel no.:604-6108515 -----Original Message----- From: Tom Dagostino [mailto:tom@teraspeed.com] Sent: Tuesday, December 05, 2006 12:17 PM To: 'Lynne D. Green'; NG,MEI-YEE; ibis-users@server.eda.org Subject: RE: [IBIS-Users] IBIS load Lynne The 50 Ohm pullup does the trick for "biasing control" of the buffer. There is no need for the 1.5K. Tom Dagostino Teraspeed(R) Labs 13610 SW Harness Lane Beaverton, OR 97008 503-430-1065 tom@teraspeed.com www.teraspeed.com Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 401-284-1827 -----Original Message----- From: owner-ibis-users@server.eda.org [mailto:owner-ibis-users@server.eda.org] On Behalf Of Lynne D. Green Sent: Monday, December 04, 2006 7:56 PM To: 'NG,MEI-YEE'; ibis-users@server.eda.org Subject: RE: [IBIS-Users] IBIS load Hello, Mei-Yee, The 1.5K resistor is needed for bias control for an open-source/open-sink buffer. In addition to that resistor, one needs a V-t load (the 50 ohms you refer to). The 50 ohm load is described in the IBIS Cookbook, http://www.vhdl.org/pub/ibis/cookbook/cookbook-v4.pdf. This means your simulation will have both resistors: the 1.5K and the 50 ohms. Once you have completed your model, please feel welcome to submit your model to the IBIS Model Review Committee, http://www.eigroup.org/ibis/support.htm. Best regards, Lynne "IBIS training when you need it, where you need it." Dr. Lynne Green Green Streak Programs http://www.greenstreakprograms.com 425-788-0412 lgreen22@mindspring.com ________________________________ From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of NG,MEI-YEE Sent: Monday, December 04, 2006 5:28 PM To: ibis-users@eda.org; ibis-users@eda.org Subject: [IBIS-Users] IBIS load Hi experts, According to the cookbook, when extracting V-T data, it is recommended to use a load circuit of 1R + 1F into manufacturer's suggested pullup resistor termination and voltage. However, when I use the suggested pullup resistor (1.5K), the rising waveform takes up to 100ns to stabilize, but the falling waveform requires less than 10ns. This creates inaccuracy due to the resolution of the points (when I use 100ns simulation time). In the IBIS model, I also included a waveform for 50Ohm pullup resistor (as recommended by cookbook). The rising waveform for this is also within 10ns. I wonder if I can generate IBIS model with ONLY 50 Ohm pullup because the resolution is more appropriate in this case? I have verified this model and the simulation shows acceptable waveforms. Kindly advice whether it is a MUST to have a 1.5K pullup resistor V-T table. Thank you. Best regards, Mei Yee Ng IC Design Engineer Illumination and Color Management Solid-state Illumination Division Avago Technologies Malaysia Tel no: +604-6108515 -------------------------------------------------------------------- |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 -------------------------------------------------------------------- |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 Mon Dec 4 21:54:55 2006
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