Nonlinear FET model in ADS. How accurate?

[gecky]

how to find nonlinear model in ads

ADS component library has a set of nonlinear models for packaged FET. How to know what the parametes used are? And, how accurate are these models? (in particular for oscillator design).

I designed a DRO using HB with one such model. The implemented hardware didn't quite work the way it should...

 

[nandopg]

Dear friend,
Normally the models built in any circuit simulator are supplied by the component's manufacturer having nothing to do with the simulator in it self. That is way you should validate a specific model before use it.
The HB algorithm used in ADS is the best one you can find in accuracy and speed, what means that if the component model is good the result that would come up from the simulation would be pretty close to that one you are going to get from measurements on the real circuit.

NandoPG

 

[abdoeng]

Re: Nonlinear FET model in @DS. How accurate?

Dear friend,
Normally the models built in any circuit simulator are supplied by the component's manufacturer having nothing to do with the simulator in it self. That is way you should validate a specific model before use it.
The HB algorithm used in @DS is the best one you can find in accuracy and speed, what means that if the component model is good the result that would come up from the simulation would be pretty close to that one you are going to get from measurements on the real circuit.

NandoPG

i agree with u,and in same link,i ask some experienced persons in that forum and they say not to take care of nonlinear module,just accurate ur result using linear one
regards

 

[nandopg]

Dear abdoeng,
I wouldn't say for not to care about nonlinear models. There are good and bad models.
For example you can use the nonlinear models of the new LDMOS transistors from Freescale that you will get a very good amplifier in the real world. Even more if you use ADS to perform the design.
Another example is a company not very well known called Excelics Semiconductor(http://www.excelics.com/). Excelics provides very good nonlinear models for their GaAs FETs and packages.
There are no question that the very best approach to design RF and Microwave stuff is to perform the device's characterization by yourself and then to use the resulting models as the inputs for your design. But in most of the cases that is impossible so, you will be OK relying on "good" nonlinear models for active devices.

Happy New Year,

NandoPG

 

[gecky]

Thanks Guys!

I'm using a NEC transistor, NE76184AS. It is no longer supported by NEC so I could not get any additional info besides the small-sig S-para. Agree that HB is very powerful tool, just abit disturbed to not know what's in that "nonlinear model" for my FET.

I need to find out the FET parameters like Rs, Rd, Cds, Cgd, Cgs.... Any reference for these?

 

[gecky]

Any suggestion for the question in the prev post?

Will be better still if someone can give the parameters for NE76184AS GaAs MESFET (NEC part).

Thanks!