Low phase noise VCO design with symmetrical inductor in CMOS 0.35-/spl mu/m technology

The VCO using differential-driven inductor obtains better performances in many folds such as phase noise, area-saving and higher harmonic rejection. Two VCOs are implemented using 0.35-/spl mu/m CMOS technology with 25-GHz-f/sub t/, 30-GHz-f/sub max/. The figure of merit (FOM) of VCO using differential-driven inductor is eight higher than using single-excited inductor and saving chip area around 50% (without including pads). The VCO with single-ended inductor achieves 320MHz tuning range with -4.5 dBm output power and phase noise about -102dBc/Hz at 1MHz offset frequency. The VCO with differential-driven inductor achieves 210MHz tuning range with -6.8 dBm output power and phase noise about -112dBc/Hz at 1MHz offset frequency. The core current of these VCOs is 8mA at 2.4-V supply voltage.