Lna rf ic cadence pss

many papers present : P1db+9.6dBm =IIP3. but,after simulation, LNA's P1db almost equal to IIP3 ; why? I want to k

now the reason.


I use three methods simulation LNA's IP3 and P1dB
1.PSS only: P1dB -15.1691, IIP3 -10.3102

2. pss+pac : P1dB -12.6293, IIP3 -1.01059

3.QPSS+pac: IIP3 -13.45

Which is correct?

Hello)
Either you simulation setup is wrong or there is something strange with your LNA. What values of P1dB and iip3 have you measured and how have you done this?

pre-simulation P1dB -15 iip3 -10, after post-simulation P1dB -10 iip3 -11

PSS swept:
50 Ohms in Resistance
1 in Port Number
Sine in Source Type
frf1 in Frequency name 1 field
frf in Frequency 1 field
prf in Amplitude1(dBm) field
Click on the Box Display Second Sinusoid
frf2 in Frequency name2 field
frf+40M in Frequency2 field
prf in Amplitude2(dBm) field

results: P1dB -12.6293 iip3: -10.3102

IIP3 and P1dB relation is valid under a input level at least 30dB below of P1dB compression point.
If P1dB compression point is -for instance- 10dBm and LNA Gain is 20dB, input level should be below -40dBm so that this relation becomes true.
Because IIP3 or OIP3 is a an extrapolation point and a circuit never reaches that pseudo nonlinear OP