Can the LNA iip3 values be positive?

[bcdeepak]

hi

i designed an inductively degenerated LNA , i got the following values, plz check...

iip3 = 2.18
oip3 = 15.6

ip1 db = -8.3
op1 db = 4.1

many LNA papers reported negative iip3,but my iip3 is positive , is it acceptable ??
i used 2.4GHz as fund1 and 2.401GHz as fund2 ( 1 MHz difference )
( LNA is designed for 2.4GHz)

 

[khouly]

LNA iip3 values

it means that , ur LNA is more linear

 

[bcdeepak]

Re: LNA iip3 values

thank you khouly

 

[radiohead]

Re: LNA iip3 values

Of course your performance on linearity is better, but in many cases that's not the main spec for LNA's. It is the noise figure you should optimize. It is easy to improve linearity by increasing the current through your transistor, but optimizing for noise involves much more. Unless you're designing an LNA for a Software Defined Radio front-end which only has little preselection from the preselection filter, linearity of the LNA is not so important.

 

[bcdeepak]

Re: LNA iip3 values

hi radiohead

thank you for ur reply

NF for the designed LNA is 1.6dB and i think it's is a good value and i wanted to check the linearity , that's why i gave the iip3 values.