PhaseNoiseSheet 1 of 14 Phase Noise. This is perhaps the most important parameter in many oscillators and it deserves an in-depth discussion on what it is, how it affects a system and how it can be minimised in an oscillator design. 1 Phase Noise An oscillator can be considered as a filtered noise generator and therefore noise will surround the carrier, equivalent to random FM and AM modulations on the ideal RF sine wave - this additional noise is known as Phase Noise. If we consider the addition of a noise voltage to a sinusoidal voltage, we must take into account the phase relationship. A phasor diagram below can be used to explain the effect. A Asin2πft 2πft (radians) Acos2πft Figure 1 Phase noise phasor diagram. A phasor with amplitude A can have any value of phase from 0 to 360 degrees as r……