1. If mixer is the load of LNA, you must account the loading of Mixer together for the opimization of NF/Gain instead of seperately.
2. There is not Cgs alone between Stage and stage in RFIC, don't forget Rg, which is always in the RF model.
3. Even CMOS RFIC, 50 ohm termination are also very common. 功率匹配 is important, but mostly of cases not required at all.