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Help, equipment/instrument selection to improve test setup IP3

Question asked by wangyiliu99 on Apr 10, 2013
Latest reply on Apr 24, 2013 by wangyiliu99
Hello, all

sorry to raise question again about the IP3 test.

In IP3 test, as for the two input tones, they can be two signal generators, or they can be signal generator(SG) plus power amplifier(PA). Here is my question

SG output at high power v.s. SG output at low power plus power amplifier. Which is better? 
For SG output at high power, the power level will be unleveled, will this lead to saturation problem? 
Besides, for SG and PA, what would be key parameters in better IP3 measurement. What came to my mind are, 
SG: phase noise(bad ones would cause problem if the two tones are close to each other), overtone/harmonics
PA: 1dB compression point, overtone/harmonics

Here, we assume the test setup is good in other parts (with filters to suppress overtone, with isolator/attenuator to improve isolation and minimize mixing of sources; power combiner with good isolation characteristics; spectrum analyzer with high dynamic range.)

Your help would be highly appreciated!