# voltage change at node, modelling leakage path

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#### ycm

##### Newbie level 5
voltage change at node?

Hi, I have a question here, see attached picture, if there is a leakage path from node V1 to ground, Vdd ramps from 0 to vdd and remain constant. Once Vdd is stable, after some time, will the voltage value at V1 change due to this leakage or the voltage at node V1 will remain the same even a leakage path there since Vdd is always there?

Re: voltage change at node?

If there is a leakage path, then this can be modeled as a large resistor. So the steady state voltage of V1 will be 0V.

Re: voltage change at node?

sounds right to me. thanks

Added after 5 hours 3 minutes:

stefannm said:
If there is a leakage path, then this can be modeled as a large resistor. So the steady state voltage of V1 will be 0V.

I forgot to ask one more question: how about the charge up? during charging period, how do we model the leakage path?

Re: voltage change at node?

stefannm said:
If there is a leakage path, then this can be modeled as a large resistor. So the steady state voltage of V1 will be 0V.

To solve this, calculate the transfer function in s-domain. then apply a unit step from 0 to Vdd denoting initial charging then use final value theorem to calculate the final value.

this will give u the zero stated by stefannm. Status
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