A VCO With Extra Cross-Coupling Path

• Published in: IEEE microwave and wireless components letters 2021-10, Vol.31 (10), p.1130-1133
• Main Authors: Wan, Cao, Xu, Taotao, Yi, Xiang, Xue, Quan
• Format: Article
• Language: English
• Subjects: CMOS; Cross coupling; Extra cross-coupling path; Figure of merit; Logic gates; low power; negative <italic xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">Gm; Phase noise; phase noise (PN); Power consumption; Power demand; startup time; Transformers; Transistors; Tuning; Voltage controlled oscillators; Wireless communication
• ISSN: 1531-1309; 2771-957X; 1558-1764; 2771-9588
• DOI: 10.1109/LMWC.2021.3102028

This letter presents a voltage-controlled oscillator (VCO) with an extra cross-coupling path realized by a novel transformer-based resonator. The extra cross-coupling can enhance the negative G_{m} and loop gain of the cross-coupled pair. The triode time of the active device during the oscillation will be reduced, resulting in better phase noise (PN) and shorter startup time than the conventional LC -VCO. Fabricated in a CMOS 65-nm process, the proposed VCO consumes 0.9 mW average dc power under a voltage supply of 0.38 V. The 1-MHz offset PN can reach −107.15 dBc/Hz at 8.38 GHz, and the corresponding figure of merit (FoM) is −186.75 dBc/Hz. The VCO's bandwidth is 34.1% ranging from 6.26 to 8.84 GHz, which corresponds an FoM T of −197.41 dBc/Hz. Thanks to the compact layout of the transformer, the VCO occupies only 0.055 mm 2 core area, resulting in a −199.35 dBc/Hz FoM A .