PURPOSE: A semiconductor device is provided to improve operation performance by feeding back a reference voltage generation state to an external system. CONSTITUTION: A comparison voltage generating unit(100) generates a plurality of comparison voltages with different levels. A reference voltage generating unit(200) receives a generation code from an external system and generates a reference voltage by selecting one comparison voltage according to the generation code. A reference voltage determining unit(300) receives a prediction reference voltage and the generation code from the external system. The reference voltage determining unit confirms whether the level of the prediction reference voltage is within a target range and outputs the confirmed result to the external system.
