A qualitative analysis of a complementary differential LC injection-locked frequency divider based on direct injection

LC injection-locked frequency dividers (ILFDs) are attractive in frequency synthesizers because of their low power consumption compared to conventional digital dividers. The drawback of LC ILFDs is the narrow widths of their locked regions. One of the techniques to increase the locking range in these dividers is to use direct injection. In this paper, we present a simplified model of direct injection in an LC ILFD. Simulation results obtained from canonical ordinary differential equations match SPICE simulations qualitatively.