Ray I have use matrix method to check the automatic calculation. The following is my netlist. V1 node1 gnd ac 1 L1 node1 node2 10mh L2 gnd node4 8.1mh L3 gnd node6 6.4mh K1 L1 L2 0.9 K2 L2 L3 0.8888888888 K3 L1 L3 0.8 R1 node2 gnd 50k R2 node4 gnd 100k R3 node6 gnd 100k The current in V1 is simulated. When there is "K3 L1 L3 0.8", the simulation result is not correct. When "K3 L1 L3 0.8" is cut, the simulation result agree with that calculated by means of matrix method and is correct. As you have pointed out, it is dangerous. I agree with you. However, in the simulation, if there are second-order or higher-order coupling, how to do? Is it a bug in the tools? Best Regards Zhangkun 2004.10.26 ----- Original Message ----- From: Ray Anderson <reanderson@xxxxxxxxxxxxx> Date: Monday, October 25, 2004 11:08 pm Subject: Re: [SI-LIST] Re: high-order coupling between inductors in hspice > . > > > > >Warning: The automatic inductance calculation is only an > estimation and is > >accurate for a subset of geometries. The second-order coupling > >coefficient is simply the product of the two first-order > coefficients,>which is not correct for many geometries. > > > > > As it says: "which is not correct for many geometries" > > I think Andy's example of L1 and L2 close and L3 far falls into > that > category. It sounds to me that the auto-calc feature described in > the > manual is dangerous at best. > > -Ray Anderson > > > > > > > > > > > > > > > > > > > > > > ------------------------------------------------------------------ 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org 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