A memory device may include: a memory cell array including a plurality of planes; and a voltage generation circuit including a master pump component and at least one or more sub-pump components that respectively correspond to the planes. During an interleaved operation, the master pump component may generate a first output voltage in response to a first pump clock, and the sub-pump components may generate second output voltages in response to second pump clocks. The master pump component and the sub-pump components may respectively provide the first output voltage and the second output voltages to the corresponding planes. During a non-interleaved operation, the master pump component and the sub-pump components may generate the first output voltage in response to the first pump clock and provide the first output voltage to a selected plane of the plurality of planes.