A 2.4-GHz linear-tuning CMOS LC voltage-controlled oscillator

ABSTRACT

This paper presents a voltage-controlled oscillator (VCO) with high linearity in frequency tuning. The VCO has two control inputs. One controls a pair of p⁺/n-well varactors to realize continuous tuning and the other controls a pair of MOS varactors for band switching. This new circuit topology achieves a good tuning nonlinearity of 1.45% and a wide total tuning range from 2.33 GHz to 2.72 GHz. The simulated phase noise is only -115.7 dBc/Hz at 600kHz offset from 2.4 GHz. Based on a 0.25-μm process, the VCO dissipates only 15mW at a 2.5-V supply voltage.

REFERENCES

• 1: T. H. Lee, The Design of CMOS Radio-Frequency Integrated Circuits. Cambridge. U.K: Cambridge Univ. Press. 1998.
• 2: M. Tiebout, H. D. Wohlmuth, and W. Simbrger, "A 1-V 51-GHz fully integrated VCO in 0.12-μm CMOS," in IEEE Int. Solid-State Circuits Conf Dig. Tech. Papers, San Francisco, CA, Feb. 2002, pp. 300--302.
• 3: P. Andreani and S. Mattisson, "A 1.8-GHz CMOS VCO tuned by an accumulation-mode varactor," in Proc. IEEE Int. Symp. Circuits and Systems, Geneva, Switzerland, May 2000, pp. 315--318.
• 4: P. Vancorenland and M. Steyaert, "A 1.57-GHz fully integrated very low phase-noise quadrature VCO," IEEE J. Solid-State Circuits, vol. 37, pp. 653--656, May 2002.
• 5: H. Wang, "A 9.8-GHz back-gate tuned VCO in 0.35- μ m CMOS," in IEEE Int. Solid-State Circuits Conf. Dig. Tech. Papers, San Francisco, CA, Feb. 1999, pp. 406--407.
• 6: J. Maget, M. Tiebout and R. Kraus, "MOS Varactors With n-and p-Type Gates and Their Influence on an LC-VCO in Digital CMOS," IEEE J. Solid-State Circuits, vol. 33, pp. 1139--1147 July 2003.
• 7: A. Hajimiri and T. H. Lee, "A general theory of phase noise in electrical oscillators," IEEE J. Solid-State Circuits, vol. 33, pp. 179--194, Feb.1998.
• 8: J. J. Rael and A. A. Abidi, "Physical processes of phase noise in differential LC-oscillators," in Proc. IEEE Custom Integrated Circuits Conf. (CICC), Orlando, FL, May 2000, pp. 569--572.