A 2.4 GHz CMOS LC VCO with Phase Noise Optimization

A 2.4 GHz low phase noise fully integrated LC voltage-controlled oscillator (VCO) in 0.18 ㎛ CMOS technology is presented in this paper. The VCO is optimized based on phase noise reduction. The design of the VCO uses differential varactors which are adopted for symmetry of the circuit, and consider AM-PM conversion due to a cross-coupled pair. The VCO is designed to draw 3 mA from 1.8 V supply voltage. Simulated phase noise is -137.3 ㏈c/Hz at 3 MHz offset. The tuning range is found to be 300 MHz range from 2.3 GHz to 2.6 GHz.