A 4.06-4.89 GHz, low phase noise symmetric complementary voltage controlled oscillator (VCO), which features an optimized capacitive feedback technique combined with RC source degeneration, is presented in this paper. Fabricated in 180nm CMOS technology, the proposed VCO obtained a measured corner frequency of 15-80 KHz. The measured phase noise at 1MHz offset from the 4.89GHz carrier is -119dBc/Hz. Occupying 0.15mm(2) in 180nm CMOS technology under 2.5mW power consumption, an area-normalized figure-of-merit (FOMA) of 197.1dBc/Hz has been achieved.