Noise property of a quadrature balanced VCO

Author

Sangsoo Ko ; Hong, S.

Author_Institution

Dept. of Electr. Eng. & Comput. Sci., Korea Adv. Inst. of Sci. & Technol., Daejeon, South Korea

Volume

15

Issue

10

fYear

2005

Firstpage

673

Lastpage

675

Abstract

A quadrature balanced voltage controlled oscillator (B-VCO) with current source switching is proposed and analyzed. This letter shows analytically that the switching improves the phase noise. A switched transistor is also used as a coupling transistor to generate quadrature signals without degrading the phase noise. To investigate the effect of quadrature coupling on the phase noise, a single B-VCO and a quadrature B-VCO are implemented with identical components in an 0.18-μm CMOS process. Both VCO cores draw about 8.8mA under a low bias voltage of 1.8V. The oscillation frequencies are 10.21GHz and 10.81GHz. The measured phase noises of the single at an offset frequency of 1MHz VCO is -114.83 dBc/Hz while that of the quadrature VCO is -116.67 dBc/Hz. The quadrature B-VCO is superior to the single B-VCO with respect to phase noise and oscillation frequency in the X-band.

Keywords

CMOS integrated circuits; MMIC oscillators; phase noise; voltage-controlled oscillators; 0.18 micron; 1.8 V; 10.21 GHz; 10.81 GHz; CMOS process; coupling transistor; current source switching; oscillation frequency; phase noise; quadrature balanced voltage controlled oscillator; quadrature coupling; quadrature signals; switched transistor; CMOS process; Circuit topology; Degradation; Feedback; Frequency measurement; Low voltage; Noise measurement; Phase noise; Signal generators; Voltage-controlled oscillators; Balanced; CMOS; current switching; noise; quadrature; transformer; voltage controlled oscillator (VCO);

fLanguage

English

Journal_Title

Microwave and Wireless Components Letters, IEEE

Publisher

ieee

ISSN

1531-1309

Type

jour

DOI

10.1109/LMWC.2005.856849

Filename

1512218