This paper presents a 7 GHz differential current-reused voltage-controlled oscillator (CR-VCO) with low power consumption and low phase noise using 0.18-μm CMOS technology. The output power of this CR-VCO is enhanced by utilizing a trifilar-transformer-feedback technique. The lower phase noise is achieved by the more symmetric voltage swings resulting from the improved balance of switching current. At a 1.5-V DC supply voltage, the power dissipation is only 3.4mW. The total tuning range is 1.4 GHz (17.9%) as the tuning voltage ranges from 0V to 1.8V. The optimum phase noise is around -117.3 dBc/Hz at a frequency offset of 1MHz from the center frequency of 7.07 GHz. The corresponding output power is around -6.8 dBm. For the proposed CR-VCO, the calculated figures-of-merit, FOM and FOMT, are -188.9 and -193.9 dBc/Hz, respectively.
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