A ow-Phase- oise CMOS Ring Oscillator with ifferential Control

A 900-MHz two-stage CMOS voltage controlled ring oscillator (VCRO) with differential control is presented. The circuit is designed in a 0.18-mum CMOS technology and operated on a 1.8-V supply voltage. The VCRO has a tuning range of 350 MHz to 1020 MHz. At 900 MHz, the phase noise of the VCRO is -109.2 dBc/Hz at 600-KHz frequency offset with power consumption of 43.7 mW