A fundamental 90-GHz CMOS VCO using new ring-coupled quad

Zuo-Min Tsai *, Chin Shen Lin, C. F. Huang, John G.J. Chern, Huei Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


A 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.

Original languageEnglish
Pages (from-to)226-228
Number of pages3
JournalIEEE Microwave and Wireless Components Letters
Issue number3
StatePublished - 1 Mar 2007


  • Cross-coupled
  • Millimeter-wave
  • Voltage controlled oscillator (VCO)


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