A semiconductor device receiving a differential data strobe signal and a method of operating the same are provided. The semiconductor device includes a differential signal phase detector receiving a differential signal including a first signal and a second signal, detecting a phase of the differential signal, and generating a mode control signal; and a receiver receiving the differential signal and a reference voltage and performing a processing operation using the differential signal in a differential mode or using the first signal and the reference voltage in a single mode according to the mode control signal. The semiconductor device may be a memory controller. Data transfer may be disabled in the single mode to prevent false data recognition due to noise.