transient options: initial conditions

[ahero_hu]

Hello,

does anyone know the exact difference between the initial condition parameters: node, DC, all, dev? and How does it impact the result of the simulation.

A very practical example is:
say a circuit needs certain time to startup, then some disturbance is injected.
I want to simulate the startup procedure only once and save the node voltages and circuit states at the last transient point. I want to use this initial condition to simulate the time slot when disturbance is injected. How does the options affect the result?

thanks.

 

[umesh49]

In general, simulators run a DC operating point analysis to determine the DC bias of circuit. While performing simulation it consider all the devices to their quiscent state. If you define the intial condition for some of parameters then it will consider those (not the quiscent state) to calculate the DC bias.
For the example you mentioned here, it would be better to run a transient analysis and capture/save the data files to read points.

 

[ahero_hu]

so it will finally result in the correct solution if the circuit is correct, and the difference is just converging time, if we choose different settings, dc or node or all?

 

[umesh49]

Yes, your final result should be the same. It will only effect initial transient responce. What is the simulation tool you are using?

 

[ahero_hu]

I am using cadence spectre