Amplitude Noise Measurement; Am Noise Measurement Block Diagrams - Keysight Technologies N5511A User Manual

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 11-1 Single Channel AM Measurement
Figure 11-2 Dual Channel AM Measurement
N5511A Phase Noise Test System User's Guide 257