Varactor characteristics, oscillator tuning curves, and AM-FM conversion

A simple analysis relates the small-signal specification of a varactor's capacitance to an oscillator's tuning curve. The notion of an effective capacitance across the amplitude of oscillation is introduced. The analysis also explains how the varactor converts AM noise on the oscillation into FM, which is phase noise. The analysis is experimentally validated.

[1]  Salvatore Levantino,et al.  Frequency dependence on bias current in 5 GHz CMOS VCOs: impact on tuning range and flicker noise upconversion , 2002, IEEE J. Solid State Circuits.

[2]  M. Tiebout,et al.  Low-power low-phase-noise differentially tuned quadrature VCO design in standard CMOS , 2001, IEEE J. Solid State Circuits.

[3]  E. Hegazi,et al.  23.4 A Filtering Technique to Lower Oscillator Phase Noise , 2008 .

[4]  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).

[5]  A. Hajimiri,et al.  Design issues in CMOS differential LC oscillators , 1999, IEEE J. Solid State Circuits.

[6]  Asad A. Abidi,et al.  RF-CMOS oscillators with switched tuning , 1998, Proceedings of the IEEE 1998 Custom Integrated Circuits Conference (Cat. No.98CH36143).

[7]  Keith A. Jenkins,et al.  Integrated RF and microwave components in BiCMOS technology , 1996 .

[8]  D. F. Peterson.  Varactor Properties for Wide-Band Linear-Tuning Microwave VCO's , 1980 .

[9]  A.A. Abidi,et al.  Noise in RF-CMOS mixers: a simple physical model , 2000, IEEE Journal of Solid-State Circuits.

[10]  F. Torrisi,et al.  Impact of indirect stability on phase noise performance of fully–integrated LC tuned VCOs , 1999, Proceedings of the 25th European Solid-State Circuits Conference.