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A 30 GHz VCO, using a transformer as the tank load and inter-stage coupling of the divider, is proposed such that the inductive load of the buffer between the VCO and the divider is eliminated and therefore chip area and power consumption can be reduced. The transformer is further reused by feedback to enhance the output swing of the VCO. Phase noise performance of the VCO can also be improved by the injection-lock mechanism from the reverse coupling of the divider. Measured results show that output phase noises of the VCO with (without) the divider are -125.1 (-118.6) dBc/Hz at 10 MHz offset frequencies from around 29.2 GHz carrier frequency. The power consumption of the VCO alone is 2.32 mW, while that of the VCO/divider increases only to 4.65 mW.