Title :
Low-phase-noise LC quadrature VCO using coupled tank resonators in a ring structure
Author :
ElSayed, Ayman M. ; Elmary, M.I.
fDate :
4/1/2001 12:00:00 AM
Abstract :
The concept of coupled resonators is employed in a ring VCO structure to reduce the phase noise. This architecture allows the design of low-phase-noise voltage controlled oscillators (VCOs) using integrated low-Q inductors. Quadrature differential outputs are also realized in this design. Two monolithic LC tanks are coupled together to implement a transimpedance resonator with an effective Q close to twice that of a single tank. In addition, the coupled tank´s transimpedance resonator provides 90° phase shift. Four such stages are cascaded in a ring structure to provide I-Q differential outputs, and to further reduce the phase noise. A prototype of the VCO is built in a 0.35-μm CMOS technology. The measured phase noise is -122 dBc/Hz at 600-kHz offset from 1.93 GHz. The VCO draws 9.2 mA from a 3-V supply, and occupies a chip area of 1.1×1.1 mm2
Keywords :
CMOS analogue integrated circuits; Q-factor; integrated circuit noise; phase noise; resonators; voltage-controlled oscillators; 0.35 micron; 1.93 GHz; 3 V; 9.2 mA; CMOS circuit; I-Q output; Q-factor; coupled resonators; integrated inductor; monolithic LC tank; phase noise; quadrature differential output; ring structure; transimpedance; voltage controlled oscillator; Band pass filters; CMOS technology; Capacitors; Coupling circuits; Frequency conversion; Phase noise; Power generation; Prototypes; Resonator filters; Voltage-controlled oscillators;
Journal_Title :
Solid-State Circuits, IEEE Journal of
