A 47 GHz $LC$ Cross-Coupled VCO Employing High- $Q$ Island-Gate Varactor for Phase Noise Reduction

A 47 GHz LC cross-coupled voltage controlled oscillator (VCO) employing the high-Q island-gate varactor (IGV) based on a 0.13 ??m RFCMOS technology is reported in this work. To verify the improvement in the phase noise, two otherwise identical VCOs, each with an IGV and a conventional multi-finger varactor, were fabricated and the phase noise performance was compared. With VDD of 1.2 V and core power consumption of 3.86 mW, the VCOs with the IGV and the multi-finger varactor have a phase noise of -95.4 dBc/Hz and -91.4 dBc/Hz respectively, at 1 MHz offset, verifying the phase noise reduction with the introduction of the high-Q IGV. The VCO with IGV exhibited an output power of around -15 dBm, leading to a FoM of -182.9 dBc/Hz and a tuning range of 3.35% (45.69 to 47.22 GHz).