Phase noise degradation at high oscillation amplitudes in LC-tuned VCO's

This paper deals with the Single Sideband to Carrier Ratio (SSCR) dependenc e on the oscillation amplitude of a fully integrated LC-tuned voltage-contr olled oscillator, fabricated in high-speed bipolar technology. As the oscil lation amplitude increases, the SSCR reaches a minimum and then steeply ris es, setting a limit to the range where better performance can be traded aga inst higher power dissipation. This dependence is fully explained by taking into account that noise and disturbances modulate the phase delay due to t he active elements. Experimental and simulation procedures for the evaluati on of this effect are presented and their impact on the circuit performance is discussed.