which method can simulate optimal source impedance of lna

[hqing]

when design LNA, it is said to size the transistors to match the optimal source impedance to get lowest NF. But I don't know which simulation can get the noise impedance of the LNA? In most cases, it is not the same with input inpedance.
i use cadence ic50, spectre and spectreRF. does anyone know which simulation can get it?

thanks a lot

 

[restart]

plot the noise circles in the smith chart NFmin is minimum noise figure in these circles. match your transistor input to this impedance.

 

[young.microwave.eng]

hi
I agree with restart.one other method is to use some special kind of matching in a way that you can tune them.
plot the noise figure in for example rectangular plot.add other diagrams such as gain,S11 and specially stability of total LNA.then manipulate the tuning of your input and output matching to reach the reasonable compromise between different parameters.If you simulate your design using microwave office,then I can help you more