1/f2 phase noise
1/f , 1/f² and 1/f³ is transpoded flicker noise to your carrier. Your semiconductor device exhibits low frequency excess noise in the form of 1/f, that modulates your carrier signal and creates AM and PM components that translate as close to carrier sidebands in your spectrum. The actuall mechanisms of how 1/f noise is transpoded to carrier noise are not clearly understoon as far as i am consern. What u mostly insterested is to reduce the flicker corner of your 1/f noise that will help your overall phase noise performance.Other factors that affect the phase noise of a VCO are the Q of your resonator, The NF of your amplifier, and the circulated power, Leesons model includes all of them in a unified formula. If u look at NIST webpage they have lots of information about phase noise.