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1 dB compression point and IIP3 difference in LNA ????

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Hello everyone,

I have a quick question.

I designed a LNA ( common Source Cascode LNA) for ultra low power application and everything is at the boundary for 220uW power dissipation.
S11=-10dB,S22=-11dB, S21=9.9dB, S12<-40dB, NF<2.5dB, Kf> 20

But my 1 dB compression point and IIP3 point do not make any sense. I am getting IIP3( -18dBm)< P1dB( -16dBm)? As I understand the difference between the 2 of them is 10dB approximately.
How can I make it correct without increasing my current ? I increased the source degeneration which improved the 1 dB compression point but no change in IIP3????????

Please advice.

Thank you in advance.
 

Can anyone help me with this question ? I really need to finish this design by this Friday ...
 

Is your result obtained by simulation or measurement? And when simulation, please describe or show your simulation setup!

- - - Updated - - -

Maybe also small schematic would help.
 

The rule of thumb is that OIP3 = P1dB + 10 dB.

You have S21 of 9.9 dB. So your OIP3= -8.1 dBm which is about 8 dB higher than your P1dB, which is not too far off.
 

The rule of thumb is only valid for single transistor amplifier WITHOUT feedback. The power of your P1dB is input or output power?
 
The power of P1dB is output and the design is Cascode LNA not single transistor.
 

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