Zhangkun, your question is not quite clear to me. As I remember the inductances L1 and L2, mutual inductance M and coupling konstant k fit into the equation M = k * SqareRoot( L1 * L2) read as "M equals k multiplied with square root of L1 multiplied with L2" if text is garbled. May be you are defining L, M and k in a different way? What is the background of your problem? Regards Thomas -----Original Message----- From: si-list@xxxxxxxxxxxxxxx [mailto:si-list@xxxxxxxxxxxxxxx] Sent: Monday, October 11, 2004 10:27 AM To: si-list@xxxxxxxxxxxxxxx Subject: [SI-LIST] Digest Number 1247 Date: Sun, 10 Oct 2004 20:05:54 +0800 From: Zhangkun <zhang_kun@xxxxxxxxxx> Subject: SPICE Question about mutuel inductance Dear All I need to express the following circuit in SPICE. I do not know how to do. Please give me some advice. L1=0nH L2=0nH M12=M21=-1nH Best Regards Zhangkun 2004.10.10 ------------------------------------------------------------------ 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