Reducing Phase Noise in Multi-Phase Oscillators

This paper investigates phase noise mechanism in arrays of resonant LC oscillators. Such arrays represent today a promising solution for the generation of multi-phase signals needed in several advanced applications. The analysis presented in this paper relies on consolidated phase-domain macromodels as well as on the original concept of noise transfer function illustrated herein. The proposed analysis sheds new light on noise generation in oscillator arrays and is able to explain certain noise degradation effects observed in nonreciprocal coupling networks. Phase-domain simulation together with noise transfer function concept provide a very efficient computational tool for rapid calculations of phase response and output noise. Thanks to this efficient tool and to the gained qualitative understanding, we are able to propose a chain array configuration enhanced by the injection of a clean, low-noise signal. In this paper, it is shown how the injected chain array can provide the prescribed phase separation while significantly reducing output phase noise.