A Compact and Low Phase Noise Square-Geometry Quad-Core Class-F VCO Using Parallel Inductor-Sharing Technique

Abstract

This article introduces a compact and low phase noise (PN) 19-GHz quad-core class-F voltage-controlled oscillator (VCO) based on a square-geometry transformer tank using the inductor-sharing technique. The proposed square-geometry transformer tank is inherently more compact than the prevalent topologies such as star geometry, dual-row geometry, and circular geometry. The inductor-sharing technique is introduced to merge neighboring inductors into smaller ones, which further reduces the chip area. Moreover, the proposed quad-core topology supports impedance boosting at harmonic frequencies without extra chip area consumption and class-F operation is adopted to achieve better PN performance. The quad-core VCO prototype is designed and fabricated in a 65-nm CMOS process. Measured performances are 17.6 to 19.4 GHz frequency range with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 137.2 dBc/Hz minimum PN at 10 MHz offset from 19 GHz carrier with 46 mW power consumption and 0.9-V supply, resulting a figure of merit (FoM) of 186.1 dBc/Hz. Thanks to the proposed square-geometry and inductor sharing technique, the proposed VCO is the smallest in quad-core VCOs with a similar operating frequency with a core chip area of 0.3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 0.3 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> and the corresponding FoM <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\mathrm{A}}$</tex-math> </inline-formula> is 196.5 dBc/Hz.