Low-power low-phase-noise differentially tuned quadrature VCOdesign in standard CMOS

摘要

This paper describes the design and optimization of VCOs withnquadrature outputs. Systematic design of fully integrated LC-VCOs with anhigh inductance tank leads to a cross-coupled double core LC-VCO as thenoptimal solution in terms of power consumption. Furthermore, a novelnfully differential frequency tuning concept is introduced to ease highnintegration. The concepts are verified with a 0.25-Μm standard CMOSnfully integrated quadrature VCO for zero- or low-IF DCS1800, DECT, ornGSM receivers. At 2.5-V power supply voltage and a total powerndissipation of 20 mW, the quadrature VCO features a worst-case phasennoise of -143 dBc/Hz at 3-MHz frequency offset over the tuning range.nThe oscillator is tuned from 1.71 to 1.99 GHz through a differentialnnMOS/pMOS varactor input