dBc

Abstract: An analysis of phase noise in differential cross-coupled inductance-capacitance (LC) oscillators is presented. The effect of tail current and tank power dissipation on the voltage amplitude is shown. Various noise sources in the complementary cross-coupled pair are identified, and their effect on phase noise is analyzed. The predictions are in good agreement with measurements over a large range of tail currents and supply voltages. A 1.8 GHz LC oscillator with a phase noise of -121 dBc/Hz at 600 kHz is demonstrated, dissipating 6 mW of power using on-chip spiral inductors.

Abstract: A completely integrated 1.8-GHz low-phase-noise voltage-controlled oscillator (VCO) has been realized in a standard silicon digital CMOS process. The design relies heavily on the integrated spiral inductors which have been realized with only two metal layers and without etching. The effects of high-frequency magnetic fields and losses in the heavily doped substrate have been simulated and modeled with finite-element analysis. The achieved phase noise is as low as -116 dBc/Hz at an offset frequency of 600 kHz, at a power consumption of only 6 mW. The VCO is tuned with standard available junction capacitances, resulting in a 250-MHz tuning range.

Abstract: We describe and demonstrate a multiloop technique for single-mode selection in an optoelectronic oscillator (OEO). We present experimental results of a dual loop OEO, free running at 10 GHz, that has the lowest phase noise (-140 dBc/Hz at 10 kHz from carrier) of all free-running room-temperature oscillators to date. Finally, we demonstrate the first fiber-optic implementation of the carrier suppression technique to further reduce the close-to-carrier phase noise of the oscillator by at least 20 dB.

Abstract: A 1.8-GHz LC VCO designed in a 0.18-/spl mu/m CMOS process achieves a very wide tuning range of 73% and measured phase noise of -123.5 dBc/Hz at a 600-kHz offset from a 1.8-GHz carrier while drawing 3.2 mA from a 1.5-V supply. The impacts of wideband operation on start-up constraints and phase noise are discussed. Tuning range is analyzed in terms of fundamental dimensionless design parameters yielding useful design equations. An amplitude calibration technique is used to stabilize performance across the wide band of operation. This amplitude control scheme not only consumes negligible power and area without degrading the phase noise, but also proves to be instrumental in sustaining the VCO performance in the upper end of the frequency range.