Calculate the intrinsic elements of FET using ADS, help!

[GameKing]

Hi everyone,

I have tried to calculate the intrinsic parameters (Cgs, Cgd, Cds, Ri, gm, gd and Tau) which are functions of the biasing conditions by ADS tool but I cannot simulate it.

How do I measure them in ADS tool?

 

[pancho_hideboo]

See http://edocs.soco.agilent.com/displ...near+FET+Model+to+Match+Measured+S-Parameters

 

[GameKing]

Thank pancho_hideboo,

However I want to measure the intrinsic parameters: Cgs, Cgd, Cds, Ri, gm, gd and Tau which are as functions of source-to-gate voltage.

 

[pancho_hideboo]

However I want to measure the intrinsic parameters: Cgs, Cgd, Cds, Ri, gm, gd and Tau which are as functions of source-to-gate voltage.

You can't measure these directly.

You have to determine these by fitting with varying bias points.

Some parameters such as gm and gd, you can measure directly.
See

 

[laperla]

I want to determine the gm,gm',gm'' in ADS
how can I calculate them?

 

[BigBoss]

I want to determine the gm,gm',gm'' in ADS
how can I calculate them?

By definition...
\[\displaystyle Gm=\frac{\partial Ids}{\partial Vgs }\]

in ADS, connect a I_Probe.i element and use diff command sequentially and find your \[GmGm'Gm''\]
I mean
\[ Gm=\frac{\partial Ic}{\partial Vbe}\]
\[ Gm'=diff(Gm)\]
\[Gm''=diff(Gm')\]

etc..

 

[laperla]

thanks for answer
I did it but when I sweep the Vgs and want to get gm vs. vgs but ADS gives me gm v. freq
how can I dram curve gm vs. Vgs?

 

[BigBoss]

thanks for answer
I did it but when I sweep the Vgs and want to get gm vs. vgs but ADS gives me gm v. freq
how can I dram curve gm vs. Vgs?

Do Swept DC simulation..Put your Vgs voltage as a variable in DC Simulation block and then obtain Ids versus Vgs...
Then differentiate it..