A 0.83-2.5-GHz continuously tunable quadrature VCO

A quadrature VCO with /spl plusmn/50% continuous 0.83-2.5-GHz tuning range is presented. It is based on a core LC-QVCO with /spl plusmn/20% tuning range, a single sideband mixer (SSBM), two frequency dividers and a multiplexer. The circuit has been implemented in a 0.13-/spl mu/m 1.2-V CMOS technology. The additional area with respect to the core LC-QVCO is 100 /spl mu/m/spl times/100 /spl mu/m. Quadrature error is less than 2/spl deg/; the phase noise is less than -120 dBc/Hz @ 1 MHz over the whole tuning range and is mainly due to the LC-QVCO. Spurs are more than 34 dB below the fundamental in the worst case.