Abstract: Based on the in-phase coupled topology, a dual-core voltage-controlled oscillator (VCO) is analyzed and designed. By connecting the outputs of two identical VCO cores in phase, the circuit can reduce the effective inductance of the resonator by half, without degrading the Q factor of the resonator and the amplitude of the output signal, thereby reducing the phase noise of the output signal. Fabricated in TPS 65 nm RFSOI CMOS technology, the chip covers an area of 1. 04 mm2, including the pads. Measurements show that the VCO can operate over a wide frequency band range from 8. 600 GHz to 12. 148 GHz (34. 2%) continuously, with a phase noise of -108. 63 dBc/ Hz@ 1 MHz obtained at 8. 841 GHz. Without the testing buffers, the VCO core circuit draws a current of 9. 2~11. 1 mA from a 1. 2 V power supply, achieving a figureof- merit-with-tuning-range (FOMT) of -183. 39 ~ -187. 13 dBc/ Hz.