Comparison of ring and LC oscillator-based ILFDs in terms of phase noise, locking range, power consumption and quality factor

In this paper, we compare a 2GHz LC oscillatorbased ILFD with a 2GHz ring oscillator-based ILFD in terms of locking range, phase noise and power consumption. We recall the definitions of open and closed loop quality factor. The open loop quality factor is convenient for relating phase noise to the circuit parameters. The closed loop quality factor is suitable for relating locking range and circuit parameters. By means of simulations, the locking range and phase noise are determined for different values of quality factor and power consumption. We show qualitatively how to tune the circuit parameters to achieve better performance.