Hi, I got an error "Singular MOM Matrix" when running Hspice fieldsolver, the source code is at below. I found that if I change trace width(W_MB) from 6 to 4 mils, it would work. Looking for inputs on causes for this error and work around. Thanks a lot, Bowen .tran 0.01n 20n V1 1 0 10 AC 1 PULSE 0 5 10N 20N 20N 500N 2U R1 1 2 1K R2 2 0 1K C1 2 0 .001U .option post=3D1 .option probe .param MB_U_GRID=3D10 .param Er_MB=3D5 .param Er_MB_SM=3D3 .param H_MB=3D2 .param W_MB=3D6 .param T_MB=3D1 .param T_Er_MB=3D0.25 .param T_PLANE=3D1.2 ********** *Materials ********** .material diel_MB Dielectric ER=3DEr_MB Losstangent=3D0.027 .material diel_MB_SM Dielectric ER=3DEr_MB_SM Losstangent=3D0.027 .material trace METAL CONDUCTIVITY=3D31meg .material gnd_plane METAL CONDUCTIVITY=3D31meg ********** *SHAPE ********** .shape rect_TL0 Rectangle Width=3D'W_MB*0.0254e-3' = Height=3D'T_MB*0.0254e-3' *********** *STACKUP *********** .Layerstack stack_TL0 +Layer=3D(gnd_plane,'0.0254e-3*T_PLANE') +Layer=3D(diel_MB,'0.0254e-3*H_MB') +Layer=3D(diel_MB_SM,'0.0254e-3*T_Er_MB') ****************** *option settings ****************** .fsoptions opt1 accuracy=3Dhigh printdata=3Dyes +COMPUTEGD=3DYES, COMPUTERS=3DYES ***************** *conductors ***************** .MODEL U_MB W Modeltype=3DFieldSolver, +LayerStack=3D stack_TL0, Fsoptions=3Dopt1, +RLGCFILE=3Dtest.rlc +conductor=3D(shape=3Drect_TL0,MATERIAL=3DTRACE, TYPE=3DSIGNAL,Origin=3D(0,'0.0254e-3*(T_PLANE+H_MB)')), +conductor=3D(shape=3Drect_TL0,MATERIAL=3DTRACE, TYPE=3DSIGNAL,Origin=3D('0.0254e-3*MB_U_GRID','0.0254e-3*(T_PLANE+H_MB)')= ), +conductor=3D(shape=3Drect_TL0,MATERIAL=3DTRACE, TYPE=3DSIGNAL,Origin=3D('2*0.0254e-3*MB_U_GRID','0.0254e-3*(T_PLANE+H_MB)= ')) .end ------------------------------------------------------------------ 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.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