My PIM Test System has a Noise Floor of -140 dBm. Can I measure a -140 dBm PIM Response?
There is a clear distinction between random noise floor (kTBF) and the “PIM Noise Floor.” The latter is more accurately restated as “Residual IM Level”. Each of these two parameters are discussed below: • The noise floor of the PIM test system is typically defined as the mean value of the measured signal when the receiver is terminated into 50 Ohms and the RF is turned off. If there is a coupling mechanism for noise from the high power amplifiers to appear in the receiver, this source of noise must also be included in the noise floor test. Noise is random and is typically due to a combination of phase noise in the local oscillator, kTBF noise from the receiver’s pre-amplifier(s), and noise from the transmitter. The noise floor of a PIM test receiver (or spectrum analyzer/LNA combination) typically varies from approximately -120 dBm to -140 dBm depending upon the selected averaging level (or resolution bandwidth). You cannot make a meaningful IM measurement at a level below the noise fl
