Jitter in ring oscillators

This paper describes a theoretical framework for analyzing and predicting jitter in ring oscillators. These oscillators are becoming more popular in low jitter applications, but the mechanisms underlying their jitter performance have been poorly understood. A comparison with analysis techniques for harmonic and relaxation oscillators shows that a different approach is needed to design for low jitter in rings. The approach taken is in the time domain, considering each delay stage to add a uniform amount of phase in a varying an amount of time. The theory is applied to experimental results from ring oscillators of several different lengths