Measurements to reveal Phase-Noise producing Mechanisms in Resonator-Oscillators

摘要

During the last decades, several theoretical models describing phase noise of oscillator signals have been established. Verification of these models has mainly been done by computer simulations. However, what is still missing is a rigorous experimental validation of diverse aspects of these models. This is not an easy job, since internal noise sources of the measurement equipment superimpose the effects to be measured. Therefore, a novel measurement method is introduced. Relatively strong, additional noise-sources are deliberately included into oscillator circuits. Controlling the power and the spectrum of these sources allows to clearly identifying the effects of these sources to the spectrum of the oscillator's output signal. This paper shows typical measurement results and their interpretations. It turns out that at least for the oscillator under test, modeling with simple additive noise might not be sufficient. Rather, multiplicative noise must also be taken into account. The consequence is that the output of oscillators might not only be affected by phase noise but also by amplitude noise. Under these circumstances, models that explicitly exclude amplitude noise in oscillators might need completion.