Design of a Low Voltage Low-Phase-Noise Complementary CMOS VCO

In this paper, the complementary CMOS LC oscillator is analyzed to design a very low-voltage low-phase-noise oscillator. Decreasing the supply voltage reduces the current consumption of the oscillator and gives effective current injection to the LC tank circuit. Effective current injection controls the noise power and the oscillator power consumption thereby reducing oscillator phase noise. Based on this structure, a 1.8 GHz oscillator with supply voltage of 1.2 v was designed. The oscillator uses an on-chip spiral inductor with Q of 8 and it has phase noise of -128.2 dBc/Hz at 1 MHz offset frequency.