Agilent Technologies E5500 Phase Noise Measurement System
12-3
AM Noise Measurement Fundamentals
Amplitude Noise Measurement
Amplitude Noise Measurement
The level of amplitude modulation sidebands is also constant with increasing
modulation frequency. The AM detector gain can thus be measured at a
single offset frequency and the same constant will apply at all offset
frequencies. Replacing the phase detector with an AM detector, the AM
noise measurement can be calibrated in the same way as PM noise
measurement, except the phase modulation must be replaced with amplitude
modulation.
The AM noise measurement is a characterization of a source. The residual
AM noise of a DUT can only be made by using a source with lower AM
noise, then subtracting that AM noise from the measured output noise of the
DUT. The noise floor of this technique is the noise floor of the source.
AM Noise
Measurement
Block Diagrams
Figure 12-1
AM Noise System Block Diagram using an E5500 Opt 001
Figure 12-2
AM Noise System Block Diagram using an External Detector