An eight-core fundamental VCO with ultralow phase noise (PN) performance is presented. Eight VCOs are in-phase coupled for low PN, and a 9-dB PN improvement is achieved. A scalable layout methodology is presented to solve the layout difficulties in multicore VCOs. Two VCO cores are connected together directly to form a VCO cell. By simply connecting N /2 VCO cells, the PN of the entire multicore VCO will achieve a 10 logN dB PN improvement compared with the single VCO core. The proposed eight-core VCO is fabricated in 65-nm CMOS and occupies 0.15 mm . The measured PN is-105.5 dBc/Hz at 1-MHz offset, with the tuning range from 62.2 to 67.3 GHz (7.9%). The VCO consumes 61.2-mW power with the figure-of-merit of-183.5 dBc/Hz at 1-MHz offset.