James and Zhangkun, In HSPICE, extremely short transmission lines can cause poor performance. This is due to the time step control algorithm when the W Element is static. Since the breakpoints are set after each minimum delay time, you will end up with too many redundant time points being calculated when the signals at the terminals of the transmission line do not vary rapidly. In the newest version, W-2005.03, a dynamic time step control algorithm was added. The necessary time points are set dynamically according to the variations of terminal currents and voltages. To enable the W element dynamic timestep control algorithm, the option WACC should be set. The syntax is: .option WACC=<value> The default for the WACC option is 0 and the original fixed timestep algorithm will be used. The option can be set between to positive, real values between 0 and 10.0. When WACC greater than 0, the dynamic timestep method is activated. Larger values result in higher performance with lower accuracy, while smaller values result in lower performance with better accuracy. For most simulations, a value of WACC=1.0 is suggested. For more accurate simulations, a value of WACC=0.1 is suggested. Tracy Barclay CAE Synopsys -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of James Church Sent: Thursday, April 07, 2005 11:47 To: zhang_kun@xxxxxxxxxx Cc: si-list Subject: [SI-LIST] Re: HSPCIE Simulation about Transmission Line Hi Zhangkun, This is a fairly well known problem with certain versions/vendor's spice algorithms. Extremely short transmission lines often have a very hard time converging and will occasionally have large errors or not converge at all. I would recommend using a distributed rlc network for these short lines. James Zhangkun wrote: >Dear all >In the current simulation, I meet one problem. When there is short transmission line in the netlist, the simulation is very slow. > >For example, in my netlist, there is the following sentence > >wline_trunk01 node1 vss rseries1 vss rlgcfile=sline_50.rlgc n=1 l=1800mil >wline_trunk02 rseries2 vss stub_01 vss rlgcfile=sline_50.rlgc n=1 l=6500mil >wline_trunk03 stub_01 vss stub_02 vss rlgcfile=sline_50.rlgc n=1 l=200mil >wline_pull stub_02 vss pull vss rlgcfile=sline_50.rlgc n=1 l=200mil > >wline_stub01 nd_out_01a vss nd_out_01 vss rlgcfile=sline_50.rlgc n=1 l=200mil >wline_stub02 nd_out_02a vss nd_out_02 vss rlgcfile=sline_50.rlgc n=1 l=200mil > >If the length of the wline_stub02 is set as 10mil, the simulation would become very slow. Could anybody tell me the reason. > >Best Regards > >Zhangkun >2005.4.7 > > >------------------------------------------------------------------ >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 > > > > ------------------------------------------------------------------ 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 ------------------------------------------------------------------ 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