A 15.6-GHz Quad-Core VCO with Extended Circular Coil Topology for Both Main and Tail Inductors in 8-nm FinFET Process

Although process scaling has brought numerous benefits in digital circuit design, it is still very challenging to design high-performance RF circuitry in advanced FinFET processes due to the increased flicker noise, reduced supply voltage, and worsened non-linearity. This paper explores the RF oscillator design in an 8-nm FinFET process and presents a quad-core oscillator with an extended circular inductor frame for both the main and tail inductors. Thanks to the extended circular topology, the tail inductance, and its quality factor are significantly increased to provide resonance efficiently at 2
^nd
-order harmonic for better flicker noise suppression. Designed and fabricated in an 8-nm FinFET process, this oscillator achieves a record-low PN of -115.4dBc/Hz at 1-MHz frequency offset and a competitive Figure-of-Merit (FoM) of -185dBc/Hz at 15.6GHz with a wide tuning range of 30%.