24 GHz CMOS Frequency Source with Differential Colpitts Structure-Based Complementary VCO for Low Phase Noise

Sung-Sun CHOI  Han-Yeol YU  Yong-Hoon KIM  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E94-C   No.5   pp.909-912
Publication Date: 2011/05/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E94.C.909
Print ISSN: 0916-8516
Type of Manuscript: BRIEF PAPER
Category: Microwaves, Millimeter-Waves
Keyword: 
complementary VCO,  frequency doubler,  gm-boosted nMOS differential Colpitts pair,  low phase noise,  resistor current sources,  

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Summary: 
In this paper, a 24 GHz frequency source for low phase noise is presented in a 0.18 µm CMOS process. The 24 GHz frequency source chip is composed of a 12 GHz voltage controlled oscillator (VCO) and a 24 GHz balanced frequency doubler with class B gate bias. Compared to a conventional complementary VCO, the proposed 12 GHz VCO has phase noise improvement by using resistor current sources and substituting the nMOS cross-coupled pair in the conventional complementary VCO for a gm-boosted nMOS differential Colpitts pair. The measured phase noise and fundamental frequency suppression are -107.17 dBc/Hz at a 1 MHz offset frequency and -20.95 dB at 23.19 GHz frequency, respectively. The measured frequency tuning range is from 23.19 GHz to 24.76 GHz drawing 2.72 mA at a supply voltage of 1.8 V not including an output buffer.