Provided are a semiconductor device and an operating method thereof. A semiconductor device includes a mixer configured to upconvert a baseband signal using a local oscillator (LO) signal; and a notch filter configured to receive the upconverted signal from the mixer and filter notch frequency components, the notch filter further configured to resonate at a fundamental frequency to provide a higher impedance and resonate at a notch frequency different from the fundamental frequency to provide a lower impedance.