Help me calculate PICs s parmeter and resistors in ADS

[abdoeng]

any help at ADS user

hi guys,i want to design atf36077 with vds=1.5,
vgs=-.2 v i want to calculate the exact s par.
at that condtions ,then calculate the
r resistors of dc simulation,i use appcad
at these condition,my question is
can i change ids to see the change
of s par.at all here my pic,pls any
error reply me

 

[khouly]

Re: any help at ADS user

u can do it by parameter sweep , sweep the current and calculate the sparameters but this is valid only if u use the nonlinear model of the transistor

but if u r using the sparameter model u cannot change the current coz the sparametrs model is for a certin bias conditions

 

[BigBoss]

Re: any help at ADS user

The S-Parameters can not be calculated, only measured under the certain conditions. Therefore , S-parameters are given as a list with the information of biasing conditions. You HAVE TO provide the SAME biasing conditions that is already defined to validate your design. Otherwise some errors will obviously come into your design.

In other hands, using nonlinear models to obtain S-Parameters under different biasing conditions WON'T give the SAME S-Parameters, it's sure.
Because S-Parameters are measured under the small signal driving and nonlinear models are NOT the SAME as well as physical behaviour which is neccessary to measure them.

To check S-parameters versus biasing, it's should be either measured or an approximation of nonlinear models should be assumed in tolerance. But this tolerance may be very large, pay attention much.

 

[khouly]

Re: any help at ADS user

it is ture i agree with u , bu it can be done just to check

and also it will be different , coz the pakaging effects

but i donot know , is it will vary large or not

 

[khouly]

Re: any help at ADS user

big boss

but how we can explain when we simulate s parameters with nonlinear model at the same operating point "DC"
we get a very close result to the s parameter model

i have verfied this with @ds and the deviation is small