LNA noise circle analysis

Hi all ...I am designing a wideband LNA and getting an NF of around 5dB. My teacher asked me to cheeck for minimun NF by doing noise circle analysis in cadence. Can somebody guide me in this regard that if am getting any specific NF then how to go for minimumNF through noise circles. I read some tutorial but could not fgure out.

Thanks

hi,

first you need to read low noise amplifier basics. how you get low noise, how to get the Noise Figure(NF) circles on the tool which you are suppose to create NF circles.
select a low noise(phemt) FET device.
see datasheet which gives the low noise figure at a certain input reflection co-eff which is called as Rho optimum.
if you match your input to this rho optimum you will get minimum noise figure as specified in datasheet.
get the s-parameter file of this FET device into ADS/microwave office and then plot NF circles for different input reflection co-eff.

an example link for an overview
www.ece.ucsb.edu/~long/ece145a/LNAdesign.pdf

thanks