Low Phase Noise, 18 kHz Frequency Tuning Step, 5 GHz, 15 bit Digitally Controlled Oscillator in 0.18 µm CMOS Technology

Ramesh K. POKHAREL  Kenta UCHIDA  Abhishek TOMAR  Haruichi KANAYA  Keiji YOSHIDA  

IEICE TRANSACTIONS on Electronics   Vol.E93-C   No.7   pp.1007-1013
Publication Date: 2010/07/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E93.C.1007
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Recent Progress in Microwave and Millimeter-Wave Technologies)
digitally controlled oscillator,  tiny capacitor,  phase noise,  frequency tuning step,  5-GHz-band wireless LAN,  0.18 µm CMOS,  

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A method to realize the fine frequency-tuning steps using tiny capacitors instead of Metal-Insulator-Metal (MIM) capacitors is proposed for a digitally controlled oscillator (DCO). The tiny capacitors are realized by the coplanar transmission lines which are arranged unsymmetrical in a 6 metal layers (M6) foundry of 0.18 µm CMOS technology. These transmission line based capacitors are designed by using electro-magnetic field simulator, and co-designed by using SPICE simulator. Finally, these capacitors are employed to design 15 bit DCO and fabricated the proposed DCO in 0.18 µm CMOS technology, and tested. The measured phase noise of DCO was -118.3 dBc/Hz (@1 MHz offset frequency), and the oscillating frequency tuned from 4.86 GHz to 5.36 GHz in the minimum frequency-tuning step of 18 kHz.