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

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 multi-core VCO. Subsequently, the mode switching technology is elucidated. On this foundation, an X-shape 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 structure adopts the 40nm process, achieving a 52.02% continuous frequency tuning range from 24.7GHz to 42.2GHz. When the bias is at 10 MHz, the phase noise varies within the range of -123dBc/Hz to -132dBc/Hz, while FoM and FoM T respectively fluctuate from 177dBc/Hz to 193dBc/Hz and 191dBc/Hz to 208dBc/Hz. Both phase noise and FoM are improved and the area is only 0.057 mm 2 .