VCO论文——Dual positive feedback VCO with noise cancellation.pdf

Dual positive feedback VCO with noise cancellation . Bui, . Choi, . Oh and . Park A low phase noise voltage controlled oscillator (VCO) is proposed by employing two positive feedback loops. One of them is used to enhance the output signal swing of the VCO while the other cancels the noise of active devices to reduce the noise contribution of those devices to the phase noise of the VCO. The proposed VCO is fabri- cated in a mm 1P6M CMOS process. The measurement result shows that the phase noise is dBc /Hz at 1 MHz offset fre- quency from the oscillation frequency of GHz while dissipating mA from a V supply voltage with a FOM of dBc / Hz. Introduction: Cross-coupled LC voltage-controlled oscillators (VCOs) have been widely used in wireless transceiver designs owing to their easy implementation, relaxed start-up condition, and differential oper- ation. However, they have limits in terms of reducing phase noise owing to the fact that the output swing of the VCOs is constrained and also noise from the current source and active devices is injected into the resonator at quite sensitive instants [1, 2] . In this Letter, we propose a VCO that has two positive feedback loops to enhance its output swing and to partially cancel the drain noise currents of active devices. As a result, the proposed VCO has low phase noise performance. Circuit desig