How to calculate impedance matching for RF power amplifier?

[minhthang_galaxy]

Hi,
At present, I am designing a RF power amplifier. I have found a paper in IEEE entitled "Design of 2.1GHz RF CMOS Power Amplifier for 3G"(attached). Here is its schematic:

I am confused about how to model MOS transistor to calculate impdedance matching. To what extend I need to model parasitic parameters?
Thanks.

 

[crutschow]

At 2.1GHz you need to model parasitics fairly accurately. For example 1pF has an impedance of 75.8Ω at 2.1GHz.

 

[minhthang_galaxy]

Hi, and thanks for the help.
Can you tell me how can we know the value above?
For example, now if the operating is 1.5GHz, then how can I know the parasitic resistance and Cgs?
If possible, please give me some references about this?