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To design a multi standard and a multi band transceiver, a quadrature voltage controlled oscillator (VCO), which has a wide tuning range, is essential, while providing low phase noise with low current consumption. In this paper, a dual band quadrature VCO in 0.18 mum CMOS process is presented. To accomplish dual band operation, reconfigurable LC tank is adopted. Series coupling transistors are attached to generate quadrature phase signal with low power consumption and low phase noise. To improve phase noise performance, current sources are eliminated and a filter inductor at the common source node is added. The measured phase noises of low frequency mode and high frequency mode are -101.81 dBc/Hz and -100.59 dBc/Hz at 10 kHz offset frequency; and -123.83 dBc/Hz and -115.06 dBc/Hz at 1 MHz offset frequency and figure of merit (FoM) at 1 MHz offset frequency of -181.8 dB and -180.5 dB with 4 mA current consumption with a 1.7 V supply.