In an operating method of a radio frequency integrated circuit (RFIC) including a transmission circuit and a reception circuit, the operating method includes receiving, from a modem, first information for setting transmission power of the transmission circuit or second information about a blocker which is a frequency signal unused by the RFIC, obtaining an allowable value of phase noise of a local oscillator included in the transmission circuit, using the first information, obtaining an allowable value of phase noise of a local oscillator included in the reception circuit, using the second information, determining a level of a driving voltage, using the obtained allowable values of the phase noises, and providing the driving voltage to the local oscillators.