This article presents a low-phase noise quadrature voltage-controlled oscillator (QVCO) in which the re-filtering technique of the side-band noise is adopted. In the proposed QVCO, besides using re-filtering technique, the passive elements replaced the noisy and lossy active coupling devices. Therefore, due to the elimination of the associate noise sources of the active coupling devices and re-filtering of side-band noise of the circuit, the proposed QVCO shows an excellent phase-noise and FOM. The proposed QVCO was implemented and simulated in TSMC 0.18 μm RF-CMOS technology. The phase noise of the proposed QVCO at 3 MHz offset frequency from the 3 GHz center frequency is ¿144 dBc/Hz, for a current consumption of 11.5 mA at a power supply of 1.8-V. Simulation results show the proposed QVCO can operate with power supply as low as 0.6 V. Monte---Carlo analyses for, 3% device mismatch and process variation, result in phase error lower than 0.8°. Generalizing the proposed coupling technique to several core VCOs very low-phase noise multiphase signals can be generated.

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