Silicon-based distributed voltage-controlled oscillators
Distributed voltage-controlled oscillators (DVCOs) are presented as a new approach to the design of silicon VCOs at microwave frequencies. In this paper, the operation of distributed oscillators is analyzed and the general oscillation condition is derived, resulting in analytical expressions for the frequency and amplitude. Two tuning techniques for DVCOs are demonstrated, namely, the inherent-varactor tuning and delay-balanced current-steering tuning. A complete analysis of the tuning techniques is presented. CMOS and bipolar DVCOs have been designed and fabricated in a 0.35-μm BiCMOS process. A 10-GHz CMOS DVCO achieves a tuning range of 12% (9.3-10.5 GHz) and a phase noise of -103 dBc/Hz at 600 kHz offset from the carrier. The oscillator provides an output power of -4.5 dBm without any buffering, drawing 14 mA of dc current from a 2.5-V power supply. A 12-GHz bipolar DVCO consuming 6 mA from a 2.5-V power supply is also demonstrated. It has a tuning range of 26% with a phase noise of -99 dBc/Hz at 600 kHz offset from the carrier.
© Copyright 2001 IEEE. Reprinted with permission. Manuscript received July 20, 2000; revised October 26, 2000. [Posted online: 2002-08-07] This work was supported in part by the Lee Center for Advanced Networking and the National Science Foundation. The authors would like to thank Conexant Systems, Newport Beach, CA for chip fabrication, and in particular S. Lloyd, R. Magoon, B. Bhattacharyya, F. In'tveld, J. Yu, and R. Hlavac for their help. They would also like to acknowledge L. Cheung, T. Hirvonen, D. Ham, H. Hashemi, S. Kee, I. Aoki, and M. Morgan of Caltech for helpful discussions and assistance with wire-bonding and measurement.