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Simulators >> Circuit Simulators >> How to set initial condition in Spectre
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Message started by wunderkind on Jul 7^th, 2010, 5:42pm

Title: How to set initial condition in Spectre
Post by wunderkind on Jul 7^th, 2010, 5:42pm

I want to set the initial condition of one node to be zero, so in ADE-->Simulation-->Convergence Aids -->Initial Condition, i set the node voltage to be zero. However, when i run transient simulation, at time 0, the voltage of this node is not zero.

How can I solve this problem? Thank you

Title: Re: How to set initial condition in Spectre
Post by wunderkind on Jul 7^th, 2010, 7:44pm

The circuit is shown below. F0 is a cccs, C8 is a cap from analogLib. I set the initial condition of meas_i to be 0. Also, ic of the cap C8 is also zero.
But the voltage of meas_i is not 0 at time=0 in transient simulation result.

Title: Re: How to set initial condition in Spectre
Post by boe on Jul 8^th, 2010, 4:20am

wunderkind,
The simulator uses a voltage source with series resistor to force the initial condition. If you have a non-zero current as DC solution, you will see the drop across the resistor as initial solution voltage.
Does this help?
BOE