Injection Locking - Injection-locked Oscillator

An injection-locked oscillator (ILO) is usually based on cross-coupled LC oscillator. It has been employed for frequency division or jitter reduction in PLL, with the input of pure sinusoidal waveform. It was employed in continuous mode clock and data recovery (CDR) or clock recovery to perform clock restoration from the aid of either preceding pulse generation circuit to convert non-return-to-zero (NRZ) data to pseudo-return-to-zero (PRZ) format or nonideal retiming circuit residing at the transmitter side to couple the clock signal into the data. Recently, the ILO was employed for burst mode clock recovery scheme.

The operation of ILO is based on the fact that the local oscillation can be locked to the frequency and phase of external injection signal under proper conditions.