Design Aspects, Part Ii

tailed discussion and analysis of the start-up and steady-state oscillation conditions for transistor LC oscillators with emphasis on CMOS devices. Part II presents both linear and nonlinear phase noise models for the parallel feedback and negative resistance oscillators. Each approach to the oscillator phase noise calculation has its own advantages and drawbacks. For example, the linear Leeson model for a parallel feedback oscillator expressed in an explicit analytical form is very simple and can explain the dependence of the oscillator phase noise on the resonant circuit loaded quality factor, signal power, active device noise figure and its low frequency flicker noise. However, it is not considering the effect of amplitude-to-phase conversion and higher order harmonics. In this case, the nonlinear Kurokawa model, developed for a negative resistance oscillator, demonstrates the explicit analytical relationship between the phase noise and oscillator stability margin, and shows the dependence of the oscillation frequency on the oscillation amplitude in a large-signal operation mode, in the form of derivatives of the device and circuit impedances. Also, the individual and joint effects of different nonlinear circuit elements, which will result in both amplitude and phase fluctuations, are discussed.