Recently, the demand on ㎜-wave (millimeter-wave) applications has increased dramatically. While circuits operating in the ㎜-wave frequency band have been traditionally implemented in Ⅲ-V or SiGe technologies, recent advances in Si MOSFET operation speed enabled ㎜-wave circuits realized in a Si CMOS technology. In this work, a 58 ㎓ CMOS LC cross-coupled VCO (Voltage Controlled Oscillator) was fabricated in a 0.13-㎛ Si RF CMOS technology. In the course of the circuit design, active device models were modified for improved accuracy in the ㎜-wave range and EM (electromagnetic) simulation was heavily employed for passive device performance predicttion and interconnection parasitic extraction. The measured operating frequency ranged from 56.5 to 58.5 ㎓ with a tuning voltage swept from 0 to 2.3 V. The minimum phase noise of -96 ㏈c/㎐ at 5 ㎒ offset was achieved. The output power varied around -20 ㏈m over the measured tuning range. The circuit drew current (including buffer current) of 10 ㎃ from 1.5 V supply voltage. The FOM (Figure-Of-Merit) was estimated to be -165.5 ㏈c/㎐.