A 24.7- to 42.2-GHz Tuning Range Quad-Core Triple-Mode VCO Using Inductor-Sharing Technique

Abstract

The voltage-controlled oscillator (VCO) with a wide tuning range and low phase noise is extensively employed in domains such as 5G, 6G, and satellite communication. This article commences with the phase noise model to conduct an analysis of the multicore VCO. Subsequently, the mode-switching technology is elucidated. On this foundation, an X-shaped compact equalizing on-chip transformer design based on the inductor sharing technique is proposed. The transformer with three modes is devised to enhance the output frequency range of the VCO. Distinct from the traditional capacitive coupling, the alteration of the effective inductance value is accomplished through the coupling between the inductors to complete the regulation of the oscillation frequency range. The proposed VCO architecture, fabricated using a 40-nm process, demonstrates a 52.3% continuous frequency tuning range, spanning from 24.7 to 42.2 GHz, as verified through post-simulation. When the bias is at a 10 MHz, the phase noise varies within the range of −123 to −132 dBc/Hz while FoM and FoM_T respectively fluctuate from 177 to 193 dBc/Hz and 191 to 208 dBc/Hz. Both phase noise and FoM are improved, with a minimal chip area of only 0.057 mm².