Finfet PTM 32nm model input capacitance?...

[siddhiqvlsi]

Hi,

I have designed Static differential cascode voltage switch logic using double gate Mosfet PTM 32nm FInfet model...I have to find the input capacitance of the same...Can anyone help me?....

Thanks in advance

 

[erikl]

Did you simulate it? In Cādence' ADE: Results -> Direct Plot -> DC , find the appropriate Fet/node and print its Cgg.

 

[siddhiqvlsi]

Did you simulate it? In Cādence' ADE: Results -> Direct Plot -> DC , find the appropriate Fet/node and print its Cgg.

Thanks for your reply...

I have simulated using hspice....have done transient analysis....

.option captab post
.print tran cap(input_node)

I have tried using the above lines to find nodal capacitance at input nodes....Is nodal capacitance same as the input capacitance or is there a separate procedure to find the same...

While using the above lines in my spice code to find Capacitance at input node I got the value as 0

Kindly respond at the earliest...Thanks in advance

 

[erikl]

...Is nodal capacitance same as the input capacitance or is there a separate procedure to find the same...

These are different values: the nodal cap. is an intrinsic value independent of extrinsic feedback (Miller, tail source, external feedback). Input capacitance considers the sum of all these caps, depending on the circuit and its operation point.

If your simulator doesn't allow for printing the input capacitance explicitly, you can run an ac analysis and inject a unit ac voltage v (1V) at the node in question. The current i into this node vs. frequency is proportional to its input conductance, i.e. to its capacitance: ωC = i/v ; v=1 , where from you can calculate its capacitance.

 

[siddhiqvlsi]

Thanks for your reply....
Is it possible to use PTM-MG model card for designing double gate mosfet?
Kindly reply at the earliest..

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Also I want to know which yields better performance?....
SOI finfet or bulk finfet model?....

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Thanks in advance...