Phenomenological study of an injection-locked CMOS LC frequency divider with direct injection

This paper reports experimental observations of injection-locking in a CMOS LC frequency divider with direct injection. Several factors are considered including the amplitude of the driving signal, the harmonic content of the driving signal, the switch size, and the forward body bias of the switch. The experiments are performed using a technique to determine rapidly the boundaries of the Arnold tongue locking regions. While some of the the observed phenomena are to be expected given the current theoretical understanding of injection-locking, others, such as the qualitatively different small- and large-signal locking regimes, have not been reported previously.