A Distributed Capacitance Analysis of Co-Planar Inductors for a CMOS QVCO with Varactor Tuned Buffer Stage

A quadrature voltage controlled oscillator (QVCO) topology exhibiting low power consumption and high phase noise performance at low supply voltages is presented. The QVCO buffer includes varactors to maximize the output voltage and minimize the current consumption. Microstrip theory and the principle of conservation of energy have been used to evaluate the distributed capacitances of symmetrical inductors to better predict the resonance frequency. The QVCO is implemented in a 0.25 μm CMOS process from Agere Systems. The total current consumption including the buffer is 5.4 mA at 1.3 V supply, where of the QVCO uses 2.0 mA. The phase noise measures below −138 dBc/Hz at 3 MHz offset frequency over the 8.9% tuning range 1.715 GHz– 1.875 GHz.

[1]  Jacques C. Rudell,et al.  An Integrated GSM/DECT Receiver: Design Specifications , 1998 .

[2]  Henrik Sjöland,et al.  Improved switched tuning of differential CMOS VCOs , 2002 .

[3]  M. K. Mills,et al.  Inductive loop system equivalent circuit model , 1989, IEEE 39th Vehicular Technology Conference.

[4]  A. Ismail,et al.  CMOS differential LC oscillator with suppressed up-converted flicker noise , 2003, 2003 IEEE International Solid-State Circuits Conference, 2003. Digest of Technical Papers. ISSCC..

[5]  A. Bonfanti,et al.  Analysis and design of a 1.8-GHz CMOS LC quadrature VCO , 2002, IEEE J. Solid State Circuits.

[6]  P. Andreani,et al.  A low-phase-noise low-phase-error 1.8 GHz quadrature CMOS VCO , 2002, 2002 IEEE International Solid-State Circuits Conference. Digest of Technical Papers (Cat. No.02CH37315).

[7]  H. Sjoland,et al.  High performance 1 V 2.4 GHz CMOS VCO , 2002, Proceedings. IEEE Asia-Pacific Conference on ASIC,.

[8]  H. Sjoland,et al.  An ultra low voltage 2.4GHz CMOS VCO , 2002, Proceedings RAWCON 2002. 2002 IEEE Radio and Wireless Conference (Cat. No.02EX573).

[9]  A. Abidi,et al.  Physical processes of phase noise in differential LC oscillators , 2000, Proceedings of the IEEE 2000 Custom Integrated Circuits Conference (Cat. No.00CH37044).

[10]  Shen-Iuan Liu,et al.  Analysis of on-chip spiral inductors using the distributed capacitance model , 2003 .

[11]  E. Hegazi,et al.  23.4 A Filtering Technique to Lower Oscillator Phase Noise , 2008 .

[12]  Behzad Razavi,et al.  Stacked inductors and transformers in CMOS technology , 2001 .

[13]  T. C. Edwards,et al.  Foundations for microstrip circuit design , 1981 .

[14]  Josep Samitier,et al.  A physical frequency-dependent compact model for RF integrated inductors , 2002 .

[15]  Peter S. Excell,et al.  Calculation of distributed capacitances of spiral resonators , 1997 .

[16]  Salvatore Levantino,et al.  A low–phase–noise 5GHz quadrature CMOS VCO using common–mode inductive coupling , 2002 .