LNA design In ADS Using HEMT

Hi all,
I am a research scholar. I would like to ask how different is designing an LNA in ADS using HEMT than using CMOS.
i have got a few very basic questions:
1) Is linear model for HEMT possible?
2)What should be the bias region to be considered?
3)from the basic requirements of matching techniques for Noise mitigation, how to obtain teh optimum Reflection coefficient of a device ?

Pls reply .
regards

1-Some foundries have linear models for their pHEMT, and surely nonlinear models.
2-Bias region is depended on what you're looking for or expecting.Normally, you should achive Gm vs Vgs curve and you decide which region you will work in.If you priority is to achieve low distortion LNA, in this case you should obtain second and third derivatives of this curve to predict IM2 and IM3 components.
3-For low noise appliaction, you may use standard techniques for other amplifiers.I mean, you draw noise circles, and find your optimum noise impedance that is seen by amplifier.But don't forget, you'll loose the gain while making noise matching.