A 1.8-GHz low-phase-noise CMOS VCO using optimized hollow spiral inductors

A completely integrated 1.8-GHz low-phase-noise voltage-controlled oscillates (VCO) has been realized in a standard silicon digital CMOS process, The design relies heavily on the integrated spiral inductors which have been realized with only two metal layers and without etching, The effects of high-frequency magnetic fields and losses in the heavily doped snbstrate have been simulated and modeled with finite-element analysis, The achieved phase noise is as low as -116 dBc/Hz at an offset frequency of 600 kHz, at a power consumption of only 6 mW, The VCO is tuned with standard available junction capacitances, resulting in a 258-MHz tuning range.