A Theoretical and Experimental Study of Injection-Locked Fractional Frequency Dividers

Based on the derived general locking equations and harmonic enhancement mechanisms of a nonlinear oscillator, injection-locked fractional frequency dividers are studied in this paper to improve the performance. Both theoretical analyses and experimental validations are performed and compared in this paper. For demonstrative purposes, fractional frequency-division ratios R=omega_in/omega_out=1.5, 2.5, 3.5, and 4.5 for a fundamental oscillating frequency f₀=2 GHz are presented and analyzed. The locking ranges of these demonstrators achieve 407, 201, 147, and 85 MHz, respectively, while consuming relatively low dc powers. Meanwhile, the noise performance of the studied divider is also analyzed and validated in this paper.