On the Impact of MOS transistor’s Gate Resistance on CMOS Oscillators beyond 10 GHz operation: Analysis and Design Strategy

Main Article Content

Ittipon Kunnapatee
Apisak Worapishet


The impact of MOS transistors’ gate resistance on the phase noise performance of CMOS LC oscillators is investigated. As oscillation frequencies approaches 10 GHz and beyond, the loss due to the gate resistance starts to dominate the total Q factor of the oscillators’ LC resonators, degrading the phase noise. A detailed analysis of the Q factor including the gate resistance is given, and this leads to a design strategy to mitigate the impact via the concept of minimum inductance. Simulations of oscillators for the oscillation frequencies ranging from 2 GHz to 32 GHz are provided to verify the impact, and to demonstrate the integrity of the analysis and design strategy.

Article Details

Research Articles


C. Cao, K. K. O, “Millimeter-Wave Voltage-Controlled Oscillators in 0.13- m CMOS Technology,” IEEE Journal of Solid-State Circuits, vol. 41, no. 6, pp. 1297-1304, June 2006.

J. Borremans, M. Dehan, K. Scheir, M. Kuijk, P. Wambacq, “VCO Design for 60 GHz Applications Using Differential Shielded Inductors in 0.13 μm CMOS,” in IEEE Radio Frequency Integrated Circuits Symposium, pp. 135-138, 2008.

L. Li, P. Reynaert, M. S. J. Steyaert, “Design and Analysis of a 90 nm mm-Wave Oscillator Using Inductive-Division LC Tank,” IEEE Journal of Solid-State Circuits, vol. 44, no. 7, pp. 1950-1958, July 2009.

T. O. Dickson, M. A. LaCroix, S. Boret, D. Gloria, R. Beerkens, S. P. Voinigescu, “30–100-GHz Inductors and Transformers for Millimeter-Wave (Bi)CMOS Integrated Circuits,” IEEE Transactions on Microwave Theory and Techniques, vol. 53, no. 1, pp. 123-133, January 2005.

D. Ham, A. Hajimiri, “Concepts and Methods in Optimization of Integrated LC VCOs,” IEEE Journal of Solid-State Circuits, vol. 36, no. 6, pp. 896-909, June 2001.

S. Jenei, S. Decoutere, S. V. Huylenbroeck, G. Vanhorebeek, B. Nauwelaers, “High Q Inductors and Capacitors on Si substrate,” in Proc. IEEE Topical Meeting Si Monolithic IC in RF Systems, pp. 64-70, 2001.

D. Dubuc, E. Toumier, I. Telliez,T. Parrs, C. Boulanger, J. Graffeuil, “High Quality Factor and High Self-Resonant Frequency Monolithic Inductor for Millimeter-Wave Si-based IC's,” in IEEE Microwave Symposium Digest, pp. 193-196, 2002.

C. H. Ng, C. S. Ho, S. F. S. Chu, S. C. Sun, “MIM Capacitor Integration for Mixed -Signal/RF Applications,” IEEE Transactions on Electronics Devices, vol. 52, no. 7, pp. 1399-1409, July 2005.

Advances Design System (ADS) 2009. Palo Alto, CA: Agilent Technol., 2009 [Online]. Available: http://www.agilent.com/find/eesof-ads