Recent Advances in Delay Cell VCOs [Application Notes]

In this article, a review of commonly used delay cell techniques in ring VCO design was covered. Design limitations such as area, power, jitter, and phase noise performance were compared for ring and LC VCOs. These parameters were compared for several delay cell topologies throughout the paper. The tunable and flexible bandwidth criterion combined with low-noise characteristics, low power, and small-area properties are the main concern of industrial engineers in design ing and choosing a proper resonator topology suitable for their respective applications. We described a num ber of the most common delay cell structures to make it easier for engineers to have a wider perspective on ring resonators.