CLOCK SELECTION DEVICE

PURPOSE:To provide a clock selection device for which the periodic fluctuation of output clock signals at the time of a clock signal selection operation is less, no fluctuation of a clock signal periodic at the time of selecting the same clock is present, a circuit scale is small and a restriction on the interval of clock signal selection is less. CONSTITUTION:This device is provided with a clock selection means 121 for selectively outputting one of the clock signals respectively generated from clock signal sources 101 and 102 as the clock signal 131 and the other one as the clock signal 132, a storage means 141 for storing clock selection instruction signals in synchronism with the clock signal 131, the storage means 142 for storing the output signals 134 in synchronism with the clock signal 132, a gate signal generation means 143 for generating gate signals by the signal 134 and the output signal 135 of the storage means 142 and a gate means for fixing the signal level of the clock signal 131 by the gate signal and outputting the clock signal 137. The signal 135 is used as the selection signal of the selection means 121.