A low-phase-noise CMOS LC oscillator with a ring structure

This LC ring oscillator is an architectural experiment to reduce the phase noise of an LC oscillator even further with a ring type structure. An LC oscillator with a special ring type structure performs phase noise filtering and attenuation. To prove the concept, several LC-ring oscillators are fabricated in 0.6 /spl mu/m, single-poly, triple-metal, CMOS. The three-stage LC-ring oscillator has -132 dBc/Hz measured phase noise at 600 kHz offset frequency from a 900 MHz carrier.