5GHz quadrature voltage-controlled oscillator using trifilar transformers

J. S. Syu*, Chin-Chun Meng, K. C. Tsung, G. W. Huang

*Corresponding author for this work

Research output: Contribution to journalArticle

12 Scopus citations


A 0.18m CMOS 5GHz quadrature voltage-controlled oscillator (QVCO) is demonstrated by using trifilar transformer coupling. The trifilar transformers composed of one primary coil and two secondary coils are used to separate the gate and drain bias for output voltage swing optimisation and also replace a conventional transistor-coupling method for quadrature output generation simultaneously. As a result, the trifilar-coupling QVCO achieves 180.1dBc/Hz figure of merit (FOM) at the supply voltage of 1.2V. The on-chip passive single sideband upconversion mixer is also demonstrated to fairly measure the quadrature accuracy of the QVCO. Thus, a 33.7dB sideband rejection ratio is achieved.

Original languageEnglish
Pages (from-to)562-563
Number of pages2
JournalElectronics Letters
Issue number9
StatePublished - 28 Apr 2008

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