A sub-harmonic oscillator using an injection-locked DCO

The paper presents a sub-harmonic injection-locked oscillator which consists of a differential comparator and even stages of inverter chain. We demonstrate that the oscillator can injection-lock on to a 1/2 and 1/3 sub-harmonic of the free running frequency signal. The oscillator is designed in a 0.35 /spl mu/m CMOS technology with a free running frequency of 950 MHz. The locking range is equal to 95 MHz and 42 MHz when the oscillator is locked at 475 MHz (1/2 sub-harmonic) and 316 MHz (1/3 sub-harmonic) respectively.