Disclosed herein is an apparatus that includes a command shifter configured to receive a command pulse and generate a plurality of first command shifted pulses in parallel, wherein each of the plurality of first command shifted pulses has the same width as the command pulse and the plurality of first command shifted pulses have different phases from each other, and a command filter configured to determine if a plurality of second command shifted pulses are generated correspondingly to the plurality of first command shifted pulses or not generated responsive to pulse overlapping among at least ones of the plurality of first command shifted pulses.