Don't forget to count in the clamp tables (and the IV tables of the [Submodel] sections). More and more of the new high speed buffers have on-die terminations, which usually are described in the one or the other clamp tables. Arpad Muranyi Intel Corporation =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D -----Original Message----- From: Dunbar, Tony [mailto:tony_dunbar@xxxxxxxxxxx] Sent: Sunday, September 29, 2002 4:02 PM To: 'SI-List' Subject: [SI-LIST] Re: Can I get this from an IBIS model? Doug, The [Pullup] and [Pulldown] tables are, effectively, impedance tables, = since they are constructed as instantaneous voltage-current points. For a = brief period of time at the start of a transition from one state to the other, both the pullup and pulldown tables are contributing to the overall = current at the IBIS model pin. However, if this is ignored the impedance of the buffer while driving the line to the high state can be determined from = the pullup table and the impedance to drive the line to the low state can be determined from the pulldown table. Through the transition, the instantaneous impdedance will, most likely, be found to be not constant, = as you might expect. Regards, Tony -----Original Message----- From: Doug Brooks [mailto:doug@xxxxxxxxxx] Sent: Saturday, September 28, 2002 12:06 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Can I get this from an IBIS model? Suppose I have an IBIS model, but not the physical part. Is there a way = I=20 can determine the output impedance of the device (and if different, the=20 output impedance for each digital state) from the IBIS model itself? I know I can build a simulation and solve for the output impedance that=20 way, but can I get it from the IBIS model itself without going through = the=20 simulation step? . And if so, where in a model do I look? Thanks for any help. Doug Brooks _________________________________________________________________________= ___ ___ UltraCAD Design announces availability of its new book "Signal Integrity = Issues in PCB Design" Details at www.ultracad.com ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: =20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages=20 Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: =20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages=20 Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu