A fully-differential CMOS Clapp VCO for IEEE 802.11a applications

Author

Shekhar, Sudip ; Aniruddhan, Sankaran ; Allstot, David J.

Author_Institution

Dept. of Electr. Eng., Washington Univ., Seattle, WA

fYear

2006

fDate

21-24 May 2006

Abstract

A fully integrated 5-6GHz differential VCO derived from the classical Clapp topology is presented in 180nm CMOS. The Clapp architecture and its characteristics are reviewed, and the location of critical portions of the circuit such as the LC-tank and varactors is discussed. The use of a Clapp VCO topology allows a larger voltage swing, which improves spectral purity and phase noise. The use of a symmetrical inductor for differential operation results in a higher Q with lower area, while providing common-mode noise rejection. The VCO achieves a simulated phase noise of -98dBc/Hz @ 100kHz & -123.1dBc/Hz @ 1MHz offsets, and draws 5mA from a 1.8V power supply. A high tuning range of 18% and FOM of 189dBc/Hz are reported. Finally, system-level simulations of a frequency synthesizer for the IEEE 802.11a bands using the Clapp VCO are presented

Keywords

CMOS integrated circuits; frequency synthesizers; microwave oscillators; phase noise; varactors; voltage-controlled oscillators; wireless LAN; 1 MHz; 1.8 V; 100 kHz; 180 nm; 5 mA; 5 to 6 GHz; CMOS Clapp oscillator; IEEE 802.11a; common-mode noise rejection; differential voltage controlled oscillators; frequency synthesizer; phase noise; spectral purity; Circuit noise; Circuit topology; Frequency synthesizers; Inductors; Phase noise; Power supplies; Tuning; Varactors; Voltage; Voltage-controlled oscillators; Clapp oscillator; frequency synthesizer; phase noise; varactors; voltage-controlled oscillators;

fLanguage

English

Publisher

ieee

Conference_Titel

Circuits and Systems, 2006. ISCAS 2006. Proceedings. 2006 IEEE International Symposium on

Conference_Location

Island of Kos

Print_ISBN

0-7803-9389-9

Type

conf

DOI

10.1109/ISCAS.2006.1693316

Filename

1693316