This paper presents an analysis of clock jitter and phase noise in single-ended and differential ring oscillators. The impulse sensitivity function (ISF) is used to derive expressions for jitter and phase noise. The effects of the number of stages, power dissipation, frequency of oscillation, and short-channel effects on jitter and phase noise are analyzed. The paper discusses the impact of substrate and supply noise on jitter and phase noise, and demonstrates how symmetry affects the upconversion of 1/f noise. New design insights are provided for low jitter/phase-noise design, and good agreement between theory and measurements is observed. The output of a practical oscillator is modeled as a function of amplitude and phase fluctuations due to internal and external noise sources. The paper derives expressions for the phase jitter of oscillators and shows how the upconversion of low-frequency noise is governed by the dc value of the ISF. The paper also discusses the relationship between jitter and phase noise, and provides expressions for the phase noise and jitter of different types of ring oscillators. The paper shows that the phase noise and jitter of ring oscillators depend on the number of stages, power dissipation, and oscillation frequency. The paper also discusses the effects of other noise sources, such as tail-current source noise and substrate and supply noise, on the jitter and phase noise of ring oscillators. The paper presents experimental results showing the phase noise and jitter of various ring oscillators. The results show that the phase noise and jitter of ring oscillators can be reduced by increasing the number of stages, but this is offset by an increase in the number of noise sources. The paper also discusses the design implications of these findings, including the trade-off between the number of stages and the phase noise and jitter of ring oscillators. The paper concludes that the analysis of jitter and phase noise in ring oscillators is essential for the design of low jitter/phase-noise oscillators.This paper presents an analysis of clock jitter and phase noise in single-ended and differential ring oscillators. The impulse sensitivity function (ISF) is used to derive expressions for jitter and phase noise. The effects of the number of stages, power dissipation, frequency of oscillation, and short-channel effects on jitter and phase noise are analyzed. The paper discusses the impact of substrate and supply noise on jitter and phase noise, and demonstrates how symmetry affects the upconversion of 1/f noise. New design insights are provided for low jitter/phase-noise design, and good agreement between theory and measurements is observed. The output of a practical oscillator is modeled as a function of amplitude and phase fluctuations due to internal and external noise sources. The paper derives expressions for the phase jitter of oscillators and shows how the upconversion of low-frequency noise is governed by the dc value of the ISF. The paper also discusses the relationship between jitter and phase noise, and provides expressions for the phase noise and jitter of different types of ring oscillators. The paper shows that the phase noise and jitter of ring oscillators depend on the number of stages, power dissipation, and oscillation frequency. The paper also discusses the effects of other noise sources, such as tail-current source noise and substrate and supply noise, on the jitter and phase noise of ring oscillators. The paper presents experimental results showing the phase noise and jitter of various ring oscillators. The results show that the phase noise and jitter of ring oscillators can be reduced by increasing the number of stages, but this is offset by an increase in the number of noise sources. The paper also discusses the design implications of these findings, including the trade-off between the number of stages and the phase noise and jitter of ring oscillators. The paper concludes that the analysis of jitter and phase noise in ring oscillators is essential for the design of low jitter/phase-noise oscillators.