Abstract: A maximum value of the number of mounted memory devices is assumed, and a value of an external delay replica is fixed and set. A desired frequency band is divided into a plurality of sub-frequency bands, and delay times of an output buffer and an internal delay replica are switched and used every sub-frequency band, thereby setting an actual maximum value and an actual minimum value to the internal delay replica. A selecting pin can select the delay time in the internal delay replica. Thus, it is possible to sufficiently ensure a set-up time and a hold time of an internal clock signal generated by a delay locked loop circuit in the latch operation in a register within a desired frequency band and with a permittable number of memory devices, irrespective of the frequency level and the number of mounted memory devices.

Abstract: First and second pre-processing flip-flops latch a command/address signal inputted to a register by a clock having a frequency of ½ of an external clock signal and an inverse clock thereof. Thus, the command/address signal is decomprossed to a set of signals which temporarily has two times. For example, one of the set of signals has only data contents of an odd-th command/address signal, and the other has only data contents of an even-th command/address signal. Since the set of signals has twice periods of the command/address signal, first and second post-processing flip-flop can latch signals in accordance with an internal clock signal generated by a delay locked loop circuit in a state in which a set-up time and a hold time are sufficiently assured.

Abstract: First and second pre-processing flip-flops latch a command/address signal inputted to a register by a clock having a frequency of 1/2 of an external clock signal and an inverse clock thereof. Thus, the command/address signal is decomprossed to a set of singals which temporarily has two times. For example, one of the set of signals has only data contents of an odd-th command/address signal, and the other has only data contents of an even-th command/address signal. Since the set of signals has twice periods of the command/address signal, first and second post-processing flip-flop can latch signals in accordance with an internal clock signal generated by a delay locked loop circuit in a state in which a set-up time and a hold time are sufficiently assured.

Abstract: A maximum value of the number of mounted memory devices is assumed, and a value of an external delay replica is fixed and set. A desired frequency band is divided into a plurality of sub-frequency bands, and delay times of an output buffer and an internal delay replica are switched and used every sub-frequency band, thereby setting an actual maximum value and an actual minimum value to the internal delay replica. A selecting pin can select the delay time in the internal delay replica. Thus, it is possible to sufficiently ensure a set-up time and a hold time of an internal clock signal generated by a delay locked loop circuit in the latch operation in a register within a desired frequency band and with a permittable number of memory devices, irrespective of the frequency level and the number of mounted memory devices.