An earphone jack circuit includes an earphone jack configured to receive an earphone plug, a frequency modulation (FM) signal processing circuit electrically connected to the earphone jack, and an amplifying circuit. The FM signal processing circuit includes a first matching circuit electrically connected to the earphone jack, and an amplifying circuit electrically connected to the first matching circuit. The first matching circuit receives an initial FM signal from the earphone jack and executes a first filtering process for the initial FM signal when the earphone plug is inserted into the earphone jack. The amplifying circuit amplifies the filtered FM signal.