Modeling and Characterization of VCOs with MOS Varactors for RF Transceivers

As more broadband wireless standards are introduced and ratified, the complexity of wireless communication systems increases, which necessitates extra care and vigilance in their design. In this paper, various aspects of popular voltage-controlled oscillators (VCOs) as key components in RF transceivers are discussed. The importance of phase noise of these key blocks in the overall performance of RF transceivers is highlighted. Varactors are identified as an important component of LC-based oscillators. A new model for accumulation-mode MOS varactors is introduced. The model is experimentally verified through measurements on LC-based VCOs designed in a standardm CMOS process.

[1]  Seong-Sik Song,et al.  An RF model of the accumulation-mode MOS varactor valid in both accumulation and depletion regions , 2003 .

[2]  Shahriar Mirabbasi,et al.  Modeling of MOS varactors and characterizing the tuning curve of a 5-6 GHz LC VCO , 2005, 2005 IEEE International Symposium on Circuits and Systems.

[3]  Michiel Steyaert,et al.  A fully integrated spiral-LC CMOS VCO set with prescaler for GSM and DCS-1800 systems , 1997, Proceedings of CICC 97 - Custom Integrated Circuits Conference.

[4]  P. Andreani,et al.  On the use of MOS varactors in RF VCOs , 2000, IEEE Journal of Solid-State Circuits.

[5]  H. Cho,et al.  A three-step method for the de-embedding of high-frequency S-parameter measurements , 1991 .

[6]  Sanjay Raman,et al.  Large-Signal Analysis of MOS Varactors , 2003 .

[7]  T. Melly,et al.  Design of high-Q varactors for low-power wireless applications using a standard CMOS process , 2000, IEEE Journal of Solid-State Circuits.

[8]  Ali Hajimiri,et al.  A general theory of phase noise in electrical oscillators , 1998 .

[9]  A. Abidi,et al.  Varactor characteristics, oscillator tuning curves, and AM-FM conversion , 2003, IEEE J. Solid State Circuits.

[10]  A. Hajimiri,et al.  Design issues in CMOS differential LC oscillators , 1999, IEEE J. Solid State Circuits.

[11]  Salvatore Levantino,et al.  A -94 dBc/Hz@100 kHz, fully-integrated, 5-GHz, CMOS VCO with 18% tuning range for Bluetooth applications , 2001, Proceedings of the IEEE 2001 Custom Integrated Circuits Conference (Cat. No.01CH37169).

[12]  Salvatore Levantino,et al.  Frequency dependence on bias current in 5 GHz CMOS VCOs: impact on tuning range and flicker noise upconversion , 2002, IEEE J. Solid State Circuits.

[13]  Sanjay Raman,et al.  Large-signal analysis of MOS varactors in CMOS -G/sub m/ LC VCOs , 2003 .

[14]  Troels Emil Kolding.  On-wafer calibration techniques for giga-hertz CMOS measurements , 1999, ICMTS 1999. Proceedings of 1999 International Conference on Microelectronic Test Structures (Cat. No.99CH36307).

[15]  E. Seebacher,et al.  MOS varactor modeling with a subcircuit utilizing the BSIM3v3 model , 2002 .