Analysis of high-order sub-harmonically injection-locked oscillators

Abstract

High-order subharmonically injection-locked oscillators have recently been proposed for low phase-noise frequency generation, with carrier-selection capabilities. This work focuses on the analysis of this frequency-synthesis procedure, with emphasis on the oscillator capability to discriminate the input tones, under the variation of a tuning voltage. The oscillator is described with an analytical envelopedomain formulation, leading to an expression for the oscillator phase shift with respect to the input source. The average of this phase shift is shown to evolve in a continuous manner in the distinct synchronization bands obtained versus the tuning voltage. Then, the subsynchronized operation at a high frequency ratio (N = 30) is considered, showing the applicability of envelopedomain simulations under various Fourier decompositions and sampling rates. The synchronization bands are obtained through the phase averaging technique. The analysis has been applied to a prototype at 2.7 GHz that has been manufactured and measured.