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[Ngspice-users] different result of the floating node
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From: Yoichiro N. <yoi...@r0...> - 2004-04-14 11:42:15
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Dear all, I am testing .ic line using ngspice-rework15. But, I get different results when I use w/ or w/o the frontend command. The test netlist is * test .model defmodel nmos level=2 tox=10n cdccut g gate 1u mmost drain gate 0 0 defmodel l=1.35u w=10u vd drain 0 5 vg g 0 5 ac 1 sin(5 2 100) .ic v(gate)=5 .tran 1m 0.2 0 1m .print tran v(gate) I know the floating node tends to cause ill-convergence. The purpose of this test is to get the effect of .ic line. The result is as following. ngspice 1 -> ictest.cir Circuit: * test ngspice 2 -> run Doing analysis at TEMP = 300.150000 and TNOM = 300.150000 Initial Transient Solution -------------------------- Node Voltage ---- ------- g 5 gate 5 drain 5 vg#branch 0 vd#branch -0.0191841 No. of Data Rows : 208 ngspice 3 -> reset ngspice 4 -> tran 1m 0.2 0 1m Doing analysis at TEMP = 300.150000 and TNOM = 300.150000 Initial Transient Solution -------------------------- Node Voltage ---- ------- g 5 gate 5 drain 5 vg#branch 0 vd#branch nan Interrupted once . . . Interrupted again (ouch) Interrupted again (ouch) Interrupted again (ouch) Interrupted again (ouch) Interrupted again (ouch) Interrupted again (ouch) Interrupted again (ouch) Interrupted again (ouch) While the first run seems to be converged, the second run, executed by the tran command from the frontend, seems to be not converged and, due to what curse, I never interrupt it by ^c. Can anyone explain this weird difference?? Thanks. |