Sadha, You can start with this article=20 http://www.edn.com/index.asp?layout=3Darticle&articleid=3DCA6544741&space= des c=3DreadersChoice There are two other articles cited in this article which should give you both the formulae and the practical insight you are looking for. -Suresh Suresh Subramaniam PhD Sr. Staff Engineer Tabula, Inc. 3250 Olcott St.=20 Santa Clara, CA 95054 Ph: 408-986-9140 x:401 Fax: 408-986-9146=20 Email: sureshs@xxxxxxxxxx =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 technical documents are available at: http://www.si-list.net 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