Injection-Locked Oscillators

Abstract

The first person to notice the phenomenon of injection locking was Christiaan Huygens, the inventor of the pendulum clock (Razavi, IEEE J Solid-State Circuits 39(9):1415–1424, 2004; Siegman in Lasers. University Science Books, Mill Valley, 1986). He was surprised to notice that different pendulum clocks attached to the same wooden beam are running perfectly synchronously. Obviously, these pulling effects between clocks are not limited to mechanical clocks. Electrical oscillators also influence each other, and even the generation of a laser beam can be injection-locked to an accurate reference laser. In literature, also many biological locking phenomena are reported, going from pulsing fireflies to our locking to the day and night rhythm (Niknejad, Injection locking, EECS 242 lecture 26, 2013).