A wide tuning-range CMOS VCO with a differential tunable active inductor

Liang Hung Lu*, Hsieh Hung Hsieh, Yu-Te Liao

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

124 Scopus citations


By utilizing a differential tunable active inductor for the LC-tank, a wide tuning-range CMOS voltage-controlled oscillator (VCO) is presented. In the proposed circuit topology, the coarse frequency tuning is achieved by the tunable active inductor, while the fine tuning is controlled by the varactor. Using a 0.18-μm CMOS process, a prototype VCO is implemented for demonstration. The fabricated circuit provides an output frequency from 500 MHz to 3.0 GHz, resulting in a tuning range of 143% at radio frequencies. The measured phase noise is from -101 to -118 dBc/Hz at a 1-MHz offset within the entire frequency range. Due to the absence of the spiral inductors, the fully integrated VCO occupies an active area of 150 × 300 μm 2.

Original languageEnglish
Article number1684139
Pages (from-to)3462-3468
Number of pages7
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number9
StatePublished - Sep 2006


  • Differential active inductors
  • Frequency tuning range
  • Miniaturization
  • Multistandard transceivers
  • Phase noise
  • Voltage-controlled oscillators (VCOs)
  • Wideband

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