A dual-band series coupled quadrature LC-VCO for IMT-A and UWB systems

In this paper, a dual-band quadrature voltage controlled oscillator (QVCO) for 3.4-3.6 GHz IMT-A and 4.2-4.8 GHz UWB applications is presented. To accomplish dual-band operation, reconfigurable LC tank is adopted. Series coupling transistors are attached to generate quadrature phase signal with low phase noise and low power consumption. To improve phase noise performance, the current source is eliminated. The simulated phase noises at 1 MHz offset frequency are -120 dBc/Hz at 3.5 GHz and -118 dBc/Hz at 4.5 GHz, respectively. Designed in 0.13 μm process, the proposed QVCO core power dissipation is 11 mW from 1.2 V power supply.