Title :
A study of phase noise in CMOS oscillators
Author_Institution :
AT&T Bell Labs., Holmdel, NJ, USA
fDate :
3/1/1996 12:00:00 AM
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-μm 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
Keywords :
CMOS analogue integrated circuits; Q-factor; UHF integrated circuits; UHF oscillators; integrated circuit noise; linear network analysis; phase noise; relaxation oscillators; time-domain analysis; voltage-controlled oscillators; 0.5 micron; 2 GHz; 900 MHz; CMOS oscillators; HF multiplicative noise; LF multiplicative noise; Q-factor; UHF IC; VCO; additive noise; first-order analysis; inductorless oscillators; linear model; linear oscillatory system; noise shaping function; phase noise; relaxation oscillator; ring oscillators; time domain simulation; Additive noise; CMOS technology; Low-frequency noise; Multi-stage noise shaping; Noise shaping; Phase noise; Predictive models; Ring oscillators; Semiconductor device modeling; Virtual prototyping;
Journal_Title :
Solid-State Circuits, IEEE Journal of
