An intuitive analysis of phase noise fundamental limits in LC oscillators

An intuitive yet sufficiently accurate analysis of the phase noise performance of various commonly used oscillator topologies, including most types of class-B (standard and with tail filter), class-C, transformer-based and class-F is used to compare their fundamental limitation. The excess noise factor, that represents the difference between the maximum achievable Figure of Merit (for a given quality factor) and the actual one is evaluated for several state-of the-art implementations.