A study of phase noise in colpitts and LC-tank CMOS oscillators

This paper presents a study of phase noise in CMOS Colpitts and LC-tank oscillators. Closed-form symbolic formulas for the 1/f/sup 2/ phase-noise region are derived for both the Colpitts oscillator (either single-ended or differential) and the LC-tank oscillator, yielding highly accurate results under very general assumptions. A comparison between the differential Colpitts and the LC-tank oscillator is also carried out, which shows that the latter is capable of a 2-dB lower phase-noise figure-of-merit (FoM) when simplified oscillator designs and ideal MOS models are adopted. Several prototypes of both Colpitts and LC-tank oscillators have been implemented in a 0.35-/spl mu/m CMOS process. The best performance of the LC-tank oscillators shows a phase noise of -142dBc/Hz at 3-MHz offset frequency from a 2.9-GHz carrier with a 16-mW power consumption, resulting in an excellent FoM of /spl sim/189 dBc/Hz. For the same oscillation frequency, the FoM displayed by the differential Colpitts oscillators is /spl sim/5 dB lower.

[1]  Jeong-Geun Kim,et al.  Ku-band InGaP-GaAs HBT MMIC VCOs with balanced and differential topologies , 2004, IEEE Transactions on Microwave Theory and Techniques.

[2]  Qiuting Huang.  Phase noise to carrier ratio in LC oscillators , 2000 .

[3]  A. Abidi,et al.  Physical processes of phase noise in differential LC oscillators , 2000, Proceedings of the IEEE 2000 Custom Integrated Circuits Conference (Cat. No.00CH37044).

[4]  Ali Hajimiri,et al.  A general theory of phase noise in electrical oscillators , 1998 .

[5]  Songcheol Hong,et al.  Ku-band InGaP-GaAs HBT MMIC VCOs with balanced and differential topologies , 2004 .

[6]  P. Schvan,et al.  A balanced 1.5 GHz voltage controlled oscillator with an integrated LC resonator , 1997, 1997 IEEE International Solids-State Circuits Conference. Digest of Technical Papers.

[7]  M. Pardoen,et al.  Fully integrated RF VCO for wireless transceivers , 1998, 1998 URSI International Symposium on Signals, Systems, and Electronics. Conference Proceedings (Cat. No.98EX167).

[8]  Thomas H. Lee,et al.  The Design of CMOS Radio-Frequency Integrated Circuits: RF CIRCUITS THROUGH THE AGES , 2003 .

[9]  K. J. McGee.  Corrections to “A General Theory of Phase Noise in Electrical Oscillators” , 1998 .

[10]  P. Andreani,et al.  On the phase-noise and phase-error performances of multiphase LC CMOS VCOs , 2004, IEEE Journal of Solid-State Circuits.

[11]  Ali Hajimiri,et al.  A noise-shifting differential Colpitts VCO , 2002, IEEE J. Solid State Circuits.