7GHz and 25.8GHz LC VCO Using 0.18 μm Mixed Signal CMOS Process

This paper presents the design and fabrication of a LC voltage-controlled oscillator (VCO) in 0.18 μm mixed signal CMOS process for operating at 7 GHz and 25.8 GHz. To obtain the high-quality factor inductor in LC resonator, patterned-ground shields (PGS) is placed under the symmetric inductor to reduce the effect of image current of resistive Si substrate. Fabricated VCO operated from 7.04 GHz to 7.34 GHz is tuned by accumulation-mode MOS varactor. The measured phase noise of 7/04 GHz VCO was -83.24 dBc/Hz at the offset of 1 MHz. Also, phase noise of 25.8 GHz VCO was -72.99 dBc/Hz at the offset of 1 MHz. The power consumption of 7 GHz and 25.8 GHz VCO was 6.48 mW and 18.61 mW, respectively