Tsai, Z.-M.Z.-M.TsaiLin, C.-S.C.-S.LinHuang, C.F.C.F.HuangChern, J.G.J.J.G.J.ChernHUEI WANG2020-06-042020-06-042007https://www.scopus.com/inward/record.uri?eid=2-s2.0-33947111012&doi=10.1109%2fLMWC.2006.890499&partnerID=40&md5=9c0a7da76ff33297d037fe7fabcb907dA new circuit topology, named ring-coupled quad for millimeter-wave voltage controlled oscillator (VCO) design, is proposed. The proposed circuit topology provides higher open loop voltage gain than conventional cross-coupled pair. The layout of the proposed ring-coupled quad is fully symmetric without additional interconnection lines. A 90-GHz VCO using 90-nm CMOS process is implemented with this ring-coupled quad. This 90-GHz oscillator demonstrates a 2.5-GHz tuning range and higher than -20 dBm output power. The proposed ring-coupled quad is suitable for the realization of high frequency VCOs. © 2007 IEEE.Cross-coupled; Millimeter-wave; Voltage controlled oscillator (VCO)journal article10.1109/LMWC.2006.8904992-s2.0-33947111012