## A study of phase noise in CMOS oscillators (1996)

Venue: | IEEE J. Solid-State Circuits |

Citations: | 70 - 2 self |

### BibTeX

@ARTICLE{Razavi96astudy,

author = {Behzad Razavi},

title = {A study of phase noise in CMOS oscillators},

journal = {IEEE J. Solid-State Circuits},

year = {1996},

pages = {331--343}

}

### Years of Citing Articles

### OpenURL

### Abstract

Abstract — This paper presents a study of phase noise in two inductorless CMOS oscillators. First-order analysis of a linear oscillatory system leads to a noise shaping function and a new definition of Q. A linear model of CMOS ring oscillators is used to calculate their phase noise, and three phase noise phenomena, namely, additive noise, high-frequency multiplicative noise, and low-frequency multiplicative noise, are identified and formulated. Based on the same concepts, a CMOS relaxation oscillator is also analyzed. Issues and techniques related to simulation of noise in the time domain are described, and two prototypes fabricated in a 0.5- m CMOS technology are used to investigate the accuracy of the theoretical predictions. Compared with the measured results, the calculated phase noise values of a 2-GHz ring oscillator and a 900-MHz relaxation oscillator at 5 MHz offset have an error of approximately 4 dB. I.

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Citation Context ...arious points in the circuit and the output spectrum is observed. This approach is justified by the fact that random Gaussian noise can be expressed as a Fourier series of sinusoids with random phase =-=[8]-=-, [9]. Since only one sinusoid is injected in each simulation, the interaction among noise components themselves is assumed negligible, a reasonable approximation because if two noise components at, s... |

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Citation Context ...requency multiplicative noise. is equal to Thus, (16) In this derivation, the thermal drain noise current of MOS devices is assumed equal to For shortchannel devices, however, the noise may be higher =-=[6]-=-. Using a charge-based model in our simulation tool, we estimate the factor to be 0.873 rather than 2/3. In reality, hot-electron effects further raise this value. Additive phase noise is predicted by... |

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Citation Context ...dentify three mechanisms leading to phase noise, and use the same concepts to analyze a CMOS relaxation oscillator. In contrast to previous studies where time-domain jitter has been investigated [1], =-=[2]-=-, our analysis is performed in the frequency domain to directly determine the phase noise. Experimental results obtained from a 2-GHz ring oscillator and a 900-MHz relaxation oscillator indicate that,... |

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Citation Context ...el, identify three mechanisms leading to phase noise, and use the same concepts to analyze a CMOS relaxation oscillator. In contrast to previous studies where time-domain jitter has been investigated =-=[1]-=-, [2], our analysis is performed in the frequency domain to directly determine the phase noise. Experimental results obtained from a 2-GHz ring oscillator and a 900-MHz relaxation oscillator indicate ... |

22 | Design of highspeed, low-power frequency dividers and phaselocked loops in deep submicron CMOS
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Citation Context ...ator. Fig. 10. stage. (b) CMOS VCO: (a) block diagram and (b) implementation of one V. CMOS RING OSCILLATOR Submicron CMOS technologies have demonstrated potential for high-speed phase-locked systems =-=[5]-=-, raising the possibility of designing fully integrated RF CMOS frequency synthesizers. Fig. 10 shows a three-stage ring oscillator wherein both the signal path and the control path are differential t... |

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Citation Context ... is also a sinusoid, but its amplitude is a function of the drain current of Since MOS thermal noise current (in the saturation region) is proportional to we use a nonlinear dependent source in SPICE =-=[7]-=- as where MHz. The factor is chosen such that when (balanced Fig. 16. Addition of output voltages of N oscillators. condition). Simulations indicate that the sideband magnitudes in the two cases diffe... |

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Citation Context ...t can be achieved for a given bias current. It is also instructive to compare the measured phase noise of the above ring oscillator with that of a 900-MHz three-stage CMOS ring oscillator reported in =-=[10]-=-. The latter employs single-ended CMOS inverters with rail-to-rail swings in a 1.2m technology and achieves a phase noise of 83 dBc/Hz at 100 kHz offset while dissipating 7.4 mW from a 5-V supply. Ass... |

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Citation Context ...s points in the circuit and the output spectrum is observed. This approach is justified by the fact that random Gaussian noise can be expressed as a Fourier series of sinusoids with random phase [8], =-=[9]-=-. Since only one sinusoid is injected in each simulation, the interaction among noise components themselves is assumed negligible, a reasonable approximation because if two noise components at, say, 6... |