A 5 GHz Band Low Noise and Wide Tuning Range Si-CMOS VCO with a Novel Varactors Pair Circuit

Tuan Thanh TA  Suguru KAMEDA  Tadashi TAKAGI  Kazuo TSUBOUCHI  

IEICE TRANSACTIONS on Electronics   Vol.E93-C   No.6   pp.755-762
Publication Date: 2010/06/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E93.C.755
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuits and Related SoC Integration Technologies)
5 GHz,  silicon complementary metal oxide semiconductor (Si-CMOS),  voltage controlled oscillator (VCO),  low noise,  wide tuning range,  

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In this paper, a fully integrated 5 GHz voltage controlled oscillator (VCO) is presented. The VCO is designed with 0.18 µm silicon complementary metal oxide semiconductor (Si-CMOS) process. To achieve low phase noise, a novel varactors pair circuit is proposed to cancel effects of capacitance fluctuation that makes harmonic currents which increase phase noise of VCO. The VCO with the proposed varactor circuit has tuning range from 5.1 GHz to 6.1 GHz (relative value of 17.9%) and phase noise of lower than -110.8 dBc/Hz at 1 MHz offset over the full tuning range. Figure-of-merit-with-tuning-range (FOMT) of the proposed VCO is -182 dBc/Hz.