How to determine the input capacitance (Cin) of a circuit using Hspice?

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chunlee

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is it possible to determine the input capacitance (Cin) of a circuit using hspice?

Thank you.
 

hspice problem

Yeah, it is possible.
You can find out the input devices and then do .op analysis of hspice.
Look in to the output file. It gives the characterisitics of each device present, including capacitance.
 

hspice problem

you can use ".option captab" to print out the capacitances at each node.
 

Re: hspice problem

what its means for node capacitance in hspice? is it node capacitance is measured from that node to ground?
 

hspice problem

Though we can use ".option captab" to print out the capacitances at each node, we do not determine the input capacitance (Cin) of a circuit using hspice, I think the input capacitance is determined by IC process.
 

hspice problem

see the .lis or .log file ,you can get the res eff or cap eff .
hspice is the best
 

Re: hspice problem

dear tony_wu_ad,

can you please tell me how to find res eff or cap eff from hspice listing file? i'm design a LNA using cmos technology and wish to find the effective capacitance and resistance looking from the input port.

thank you.

regards,
chunlee
 

hspice problem

The capacitances at each node and at each device are printed out in the .lis files.
 

Re: hspice problem

hallo,
I think you can find value of capacitances in .lis file.
but i think that we can't find value of small signal input and output resistances. If I am wrong please respected member help me to find out resistance.

Added after 52 seconds:

hallo,
I think you can find value of capacitances in .lis file.
but i think that we can't find value of small signal input and output resistances. If I am wrong please respected member help me to find out resistance.
 

Re: hspice problem

You can use .tf in Hspice, then you can get the DC small signal input &output resistance,also DC gain.
 

hspice problem

do DC analyze , and select .op option.
 

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