A 1.24-GHz monolithic CMOS VCO with phase noise of -137 dBc/Hz at a 3-MHz offset

For the first time, a 1.24-GHz CMOS voltage-controlled oscillator (VCO) with an integrated resonator which satisfies the global system for mobile communications (GSM) phase noise requirement at a 3-MHz offset is presented. The measured phase noise is -88, -125, and -137 dBc/Hz at 10-kHz, 600-kHz, and 3-MHz offsets, respectively. The VCO is implemented in a low-cost 0.8-mu m foundry CMOS process exclusively using pMOS transistors which have greater than one order of magnitude lower 1/f noise than that of nMOS transistors. The tuning range is similar to 130 MHz for the control voltages between 0.5 and 3.0 V, The VCO core runs on 22 mA from a 3-V power supply.