It depends on application of your LNA.
my standard is IEEE802.15.4 with 0dB rejection for adjacent channel and 30dB rejection for alternate channel. But I don't follow how these are related and why exactly!
(1) Frequency of RF1 and RF2
(2) Local Frequency
(3) Frequency of IF1 and IF2.
here is all info:
Harmonic Balance input frequencies:
Freq[1]=2441 MHz (upper fundamental)
Freq[2]=2439 MHz (Lower fundamental)
Freq[3]=2436 MHz (Local oscillator)
I swept both input RF tones together and equally but surprisingly fundamentals at the output are not the same(figure 1)! but then when they mix with LO they become equal(figure2)!
and about intermodulation products:
Upper IMD3=2*2441-2439=2443 MHz After mixing(IF IMD)=7 MHz
Lower IMD3=2*2439-2441=2437 MHz After mixing(IF IMD)=1 MHz
(figure3 shows IM products at RF and figure4 shows them at IF)
Why they are not equal!?
Note:
1- I tried smaller fundamental spacings: (upper=2440.01MHz) and (lower=2439.99MHz). No change!
2- I checked the input P_ntone source.
3- It's just a regular single Balanced but I got the same issue for other works