Design of a 2.5-GHZ QVCO robust against high frequency substrate noise

This work presents the design procedure followed to obtain a low‐power voltage‐controlled oscillator (VCO) robust against high‐frequency substrate noise, using as a demonstrator a 2.5 GHz VCO with quadrature outputs (QVCO) based on a 5‐GHz LC tank resonant VCO (LC‐VCO) and frequency divider. A simple, intuitive, and easy to handle analytical model is proposed to identify the design parameters that contribute to the performance degradation of LC‐VCOs due to the effect of high frequency substrate noise. The guidelines obtained have been applied in the design of the low‐power QVCO. Finally, the work discusses several trade‐offs that can be used to maximize the immunity of a LC‐VCO against substrate noise. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26043