Analysis and design of a dual band reconfigurable VCO

Abstract

A systematic approach to the design of reconfigurable LC VCOs is proposed in this paper. The focus is on the choice of the reactive element of the tank most suited to switch the oscillation frequency. The optimum is the component that determines the tank Q. As an example, the design of a GSM900/1800 VCO in a 0.13 /spl mu/m CMOS technology, switching a series inductor, is discussed. At this frequency, the tank Q is roughly the inductor Q, and series inductor switching allows area savings with respect to parallel switching.