High-Frequency Low-Noise Voltage-Controlled LC-Tank Oscillators Using a Tunable Inductor Technique

Ching-Yuan YANG  Meng-Ting TSAI  

IEICE TRANSACTIONS on Electronics   Vol.E89-C   No.11   pp.1567-1574
Publication Date: 2006/11/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e89-c.11.1567
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Novel Device Architectures and System Integration Technologies)
LC VCO,  tunable inductor,  high Q,  transformer,  

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This paper describes 3-GHz and 7-GHz tunable-inductance LC-tank voltage-controlled oscillators (VCOs) implemented in 0.18-µm CMOS technology. Unlike the traditional tuning method by a varactor, a tunable inductor is employed in the VCO by using a transformer to compensate for the energy loss. The VCO facilitates the tuning frequency and low noise of the output signals, together with a variable inductor which satisfies both criteria. The 3-GHz VCO using a symmetry transformer provides the tuning range of 2.85 to 3.12 GHz at 1-V supply. The power consumption is 4.8 mW while the measured phase noise is -126 dBc/Hz at 1-MHz offset from a 2.85-GHz carrier. A small-area stacked transformer is employed in the 7-GHz VCO, which achieves a tuning range of 6.59 to 7.02 GHz and measured phase noise of -114 dBc/Hz at 1-MHz offset from a 6.59-GHz carrier while consuming 9 mW from a 1.2-V supply.