IEICE Electronics Express
Online ISSN : 1349-2543
ISSN-L : 1349-2543
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A linearized tuning varactor for voltage controlled oscillator
Xincun JiXiaojuan XiaShipu GuYufeng Guo
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2017 Volume 14 Issue 17 Pages 20170730

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Abstract

A linearized tuning varactor for the voltage controlled oscillator (VCO) is proposed in this paper. The capacitance-voltage (C-V) curve is linearized by combining an accumulation MOSFET (AMOS) and PMOS in parallel to form the varactor. Two ring voltage controlled oscillators (ring VCOs) are fabricated and measured with a standard 65-nm CMOS process. They are both identical except for the varactor. The first VCO uses the proposed varactor, and the second one is tuned by a conventional AMOS-only varactor for reference. The ring VCO with the proposed varactor operates from 500.5 to 807.6 MHz, and the VCO gain (KVCO) varies from 183 to 284 MHz/V. Comparing the reference VCO with the AMOS-only varactor, the measured KVCO variability is reduced by 82%. The phase noise is between −89 dBc/Hz and −92 dBc/Hz at 1 MHz offset while dissipating 0.8 mA from a 1.2-V supply.

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© 2017 by The Institute of Electronics, Information and Communication Engineers
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