Dual Band CMOS Quadrature VCO using Reconfigurable LC Tank and Coupled Transistors

To qualify the condition of a multi standard and a multi band transceiver, a quadrature voltage controlled oscillator (VCO), which has a wide and proper tuning range, is necessary, while providing high phase noise performance and consuming low current. In this paper, a dual band quadrature VCO in 0.18 μm CMOS process is proposed. To attain the dual band operation, a reconfigureurable LC tank is adopted. To generate quadrature phase signal with low phase noise and low power consumption, series coupling transistors are attached. To enhance the phase noise performance, a current source of the source of the nmos transistor is excluded, and a filter inductor at the common source node is included. The measured phase noises of low frequency band and high frequency band are -123.8 dBc/Hz and -115.06 dBc/Hz at 1 MHz offset frequency and figureure-of-merit (FoM) of -181.8 dB and -180.5 dB with 4 mA current consumption with a 1.7 V supply.