A low noise bulk-coupled Colpitis CMOS quadrature VCO

Yi Hsien Cho, Fong Cheng Chang, Ming Fong Lei, Ming Da Tsai, Hong Yeh Chang, Huei Wang

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

12 Scopus citations


This paper proposes a quadrature voltage-controlled oscillator (QVCO) using 0.18-μm 1P6M standard CMOS process. The QVCO is realized by combining two differential oscillators via the bulk terminals. Using this approach, we can reduce the power dissipation and remove the noise from the additional coupling transistors compared with conventional QVCOs. To improve the phase noise, the oscillator is composed of Colpitis topology for lower phase noise than its cross-coupled counterpart. Moreover, the Colpitts oscillator adopts only PMOS to achieve a better phase noise performance because PMOS has less 1/f noise than NMOS. The VCO operates from 4.9 to 5.5 GHz with more than 11 % tuning range. The measured phase noise at 600-kHz offset is -117 dBc/Hz at 5.2 GHz. The QVCO dissipates 10.8 mW at 1.8 V and achieves a good FOM of 185 dB.

Original languageEnglish
Title of host publication2006 Asia-Pacific Microwave Conference Proceedings, APMC
Number of pages4
StatePublished - 2006
Event2006 Asia-Pacific Microwave Conference, APMC - Yokohama, Japan
Duration: 12 Dec 200615 Dec 2006

Publication series

NameAsia-Pacific Microwave Conference Proceedings, APMC


Conference2006 Asia-Pacific Microwave Conference, APMC


  • CMOS integrated circuit
  • Colpitis oscillator
  • Phase noise
  • Quadrature


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