I think you got it. Cadence Spectre represents each port with a positive and a negative terminal. This is just like, if you were measuring these s-parameters using a VNA and microprobes. The microprobes each have a positive and a negative terminal. By the way, some circuit simulators that can handle s-parameters choose to combine all the negative terminals into one common "reference" terminal. Spectre keeps them separate. Regards, Patrick Zilaro SI Packaging Engineer Broadcom Corporation -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Amitava Bhaduri Sent: Thursday, October 30, 2003 2:03 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] N-port problem in interconnects Hi, I am trying to model the interconnects using the "nport" feature of spectre. Take for example I have 2 conductors (A1-B1 and A2-B2). A1, B1, A2, B2 are connected to other circuit elements, like transistors for example. I am trying to model only the interconnect portion. _ _ B1 | | B2 | | | | | | | | | |_____________ | |_____________ |_____________ | |____________ | | | | | | | | | | | | | | | | | |_| A1 |_| A2 I am able to obtain a (2 x 2) impedance matrix [Z] for this 2-conductor system. Using the formula (Z-1)(Z+1)^-1, the impedance parameters can be converted to s-parameters (as "nport" of spectre operates on s-parameters). The problem is how do I represent this 2-conductor system in spectre "nport" format. If you do "spectre -help nport" you will see that the instance statement looks like: Name ( t1 b1 [t2] [b2] ... ) nport <parameter=value> ..., where the terminals should be given in pairs. Can this 2-conductor system be realized as 2-port network? What would the common terminals be (-ve terminal) in this case? In this 2-port interconnect network can I represent the first port as (A1, B1) where A1 is +ve terminal and B1 is -ve terminal, while the second port being (A2, B2) where A2 is +ve terminal and B2 is -ve terminal? (note: this is only an instance of a 2-conductor system. The same problem can be extended for any "n-conductor system", where n=1,2,3,4,5...etc) Would appreciate any help on this. Thanks, Amit Amitava Bhaduri Research Assistant 527 ERC University of Cincinnati OH - 45220 ph : 513-556-3025 ------------------------------------------------------------------ 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 ------------------------------------------------------------------ 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