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Class-C Harmonic CMOS VCOs, With a General Result on Phase Noise

Author

Summary, in English

A harmonic oscillator topology displaying an improved

phase noise performance is introduced in this paper.

Exploiting the advantages yielded by operating the core transistors

in class-C, a theoretical 3.9 dB phase noise improvement

compared to the standard differential-pair LC-tank oscillator

is achieved for the same current consumption. Further benefits

derive from the natural rejection of the tail bias current noise,

and from the absence of parasitic nodes sensitive to stray capacitances.

Closed-form phase-noise equations obtained from a

rigorous time-variant circuit analysis are presented, as well as a

time-variant study of the stability of the oscillation amplitude,

resulting in simple guidelines for a reliable design. Furthermore,

the analysis of phase noise is extended to encompass a general harmonic

oscillator, showing that all phase noise relations previously

obtained for specific LC oscillator topologies are special cases of a

very general and remarkably simple result.

Two prototypes of the (voltage-controlled) oscillator are

implemented in a standard RF 0.13 m CMOS technology.

They are tunable over the frequency bands 4.90-5.65 GHz and

4.50–5.00 GHz, respectively, and display an average phase noise

lower than 130 dBc/Hz @ 3 MHz from the carrier with a power

consumption of 1.4 mW, for a state-of-the-art figure-of-merit

ranging from 193.5 dBc/Hz to 196.0 dBc/Hz.

Publishing year

2008

Language

English

Pages

2716-2729

Publication/Series

IEEE Journal of Solid-State Circuits

Volume

43

Issue

12

Document type

Journal article

Publisher

IEEE - Institute of Electrical and Electronics Engineers Inc.

Topic

  • Electrical Engineering, Electronic Engineering, Information Engineering

Status

Published

Research group

  • Data converters & RF

ISBN/ISSN/Other

  • ISSN: 0018-9200