A 3 mW/GHz near 1-V VCO with low supply sensitivity in 0.18-µm CMOS for SoC applications

A novel pseudo-differential ring Voltage Controlled Oscillator (VCO) with near 1-V supply is realized in standard 0.18-mum CMOS with no low Vt options. The VCO core structure improves the supply noise rejection by 20 dB. The pseudo-differential structure provides rail-to-rail swing, which improves phase noise and eliminates the level shifter needed in fully differential designs. Several new topologies, suitable for near 1-V supply, are proposed for the V-to-I converter and the additional shunt supply regulator that provides additional supply noise isolation. With a 1 V supply, the whole VCO consumes less than 3 mW for 1 GHz operation and provides eight clock phases. The compatibility with digital supply and low supply sensitivity enables it to be an ideal candidate for large System-on-Chip (SoC) integrations.