Design and Optimization of an Area Efficient Ultra-Low Voltage Differential Ring VCO with Wide Tuning Range for PLL Applications

This article presents the design and analysis of a 90nm CMOS three-stage differential ring voltage-controlled oscillator (VCO) functioning at an impressively low supply voltage of 0.8V. The VCO demonstrates favorable power efficiency with a power consumption of only 3.2mW at 5GHz and 1.2mW at 2.4GHz. The tuning range extends from 0.396 GHz to 7.544 GHz, providing remarkable versatility for a variety of applications. The proposed structure exhibits a good phase noise characteristic, achieving -83.94dBc/Hz and -87.20 dBc/Hz at 5GHz and 2.4GHz, respectively, at an offset frequency of 1MHz. The calculation of the figure of merit (FOM) provides a comprehensive evaluation of the VCO’s performance, yielding values of -152.87 dBc/Hz for 5 GHz and -154.01 dBc/Hz for 2.4 GHz, indicating its robustness and suitability for precision frequency synthesis. The VCO occupies an exceptionally small amount of area, specifically 0.00067 mm
²
. In addition, the model’s performance is assessed, and its compatibility is examined through a comprehensive analysis involving process corner evaluation, temperature sweeping and Monte Carlo analysis across diverse environmental conditions. This study demonstrates that the proposed VCO has the potential to significantly enhance the effectiveness of Phase-Locked Loops (PLLs) and other frequency synthesis applications in power-sensitive and high-frequency communication systems.