1-GHz and 2.8-GHz CMOS injection-locked ring oscillator prescalers

We implemented prescalers that can operate up to 2.8-GHz by exploiting the injection locking phenomena in differential CMOS ring oscillators. We tested a 5-stage, 1-GHz injection-locked modulo-8 prescaler fabricated in a 0.24-/spl mu/m CMOS technology that consumes 350 /spl mu/W of power and occupies 0.012 mm/sup 2/ of die area. The locking range is 20 MHz and the locked phase noise is -110 dBc/Hz @ 100 kHz. A 2.8-GHz, 3-stage, modulo-4 divider is also presented.