So far I have seen two types of schmitt trigger circuits in CMOS, one having input fully resistantly isolated from its output, while the other one would have a transient connection during switching. I suspect the slow down effect might be on the second type only, in view of Parthasarathy's saying that it does not work in lower frequency. Rgds, Raymond "Ingraham, Andrew" <Andrew.Ingraham@xxxxxx> on 20/12/2002 09:31:30 Please respond to Andrew.Ingraham@xxxxxx To: si-list@xxxxxxxxxxxxx cc: (bcc: Raymond Leung/sdc) Subject: [SI-LIST] Re: Hspice Limitations > 2. The load capacitor on the oscillator is 15pf which > is huge compared to the capacitor load effect the > schmitt trigger can ever think of producing. By "loading down" the oscillator, it could be capacitance (such as a typo in the model that causes it to have huge capacitance) ... but it also could be something other than capacitance. For example, if a power source doesn't get to the Schmitt circuit, that would make it have no output, and might cause it to nonlinearly load down the oscillator circuit. Andy ------------------------------------------------------------------ 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