Design of 50-GHz Low Phase Noise VCO Employing Two-Branches DGS Resonator in 0.18-μm CMOS Technology

This letter presents a $V$ -band low phase noise voltage-controlled oscillator (VCO) design using a novel integrated two-branches defected ground structure (DGS) resonator in 0.18- $\mu \text{m}$ complementary metal-oxide-semiconductor (CMOS) technology. The proposed DGS resonator is realized in the top metal layer (M6) which has not only a higher quality factor than its predecessors but is also effective to reduce the length of interconnects. The measured carrier frequency and phase noise are 49 GHz and −122.05 dBc/Hz (−102.58 dBc/Hz) at 10-MHz (1-MHz) offset frequencies, respectively. The VCO core consumes 5.5 mW of dc power from the dc supply, which results in a figure of merit (FoM) of −189 dBc/Hz. The proposed VCO using the two-branches DGS resonator may give an alternative low-cost solution for designing a high-performance VCO or frequency synthesizer at $V$ -band and beyond.