id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
2014	Modelica.Electrical.Spice3.Examples.CascodeCircuit	Jens Frenkel	Volker Waurich	"The model Modelica.Electrical.Spice3.Examples.CascodeCircuit fails in simulation because the equations 

{{{
4/8 (1): J1.icGD = J1.cc.cGD * der(J1.vGD)
5/9 (1): J1.icGS = J1.cc.cGS * der(J1.vGS)
13/21 (1): J2.icGD = J2.cc.cGD * der(J2.vGD)
14/22 (1): J2.icGS = J2.cc.cGS * der(J2.vGS)
}}}

are not solvable for the der(...) variables because J*.cc.cGD is zero.

If you take a look at the equation

{{{
22/30 (1): J2.vGS = v_sin.VO + (if time < v_sin.TD then 0.0 else v_sin.VA * exp((v_sin.TD - time) * v_sin.THETA) * sin(6.283185307179586 * v_sin.FREQ * (time - v_sin.TD)))
}}}

you see that the state candidate J2.vGS is the only unkown variable in the equation. Hence the variable J2.vGS is purely algebraic and the variable der(J2.vGS) is known as 

{{{
der(J2.vGS) = if time < v_sin.TD then 0.0 else v_sin.VA * (exp((v_sin.TD - time) * v_sin.THETA) * 6.283185307179586 * v_sin.FREQ * cos(6.283185307179586 * v_sin.FREQ * (time - v_sin.TD)) + (-v_sin.THETA) * exp((v_sin.TD - time) * v_sin.THETA) * sin(6.283185307179586 * v_sin.FREQ * (time - v_sin.TD)))
}}}

Subsequently the variable J2.igsgmin is known from equation

{{{
15/23 (1): J2.igsgmin = 0.000000000001 * J2.vGS
}}}

"	task	closed	normal	1.9.1	Backend	trunk	fixed	index reduction, remove simple equations	christian.schubert@…