Patent ID: 8228747

Claim:
A delay adjustment device that is connected to a memory, and adjusts a timing to retrieve data with a data signal and a data strobe signal output from the memory, the delay adjustment device comprising: a data retrieve unit that receives the data signal and the data strobe signal, and outputs a data value of the data signal in accordance with the data strobe signal; and a control unit that issues a read command to the memory, retrieves values of the data strobe signal in response to the read command to calculate flight time, and controls a valid period of the data strobe signal based on the flight time, wherein the control unit comprises: a valid signal output unit that outputs a valid signal to indicate the valid period of the data strobe signal; a strobe value retrieve unit that retrieves the values of the data strobe signal in accordance with the valid signal; and an adjustment unit that issues the read command, instructs a timing to output the valid signal to the valid signal output unit, retrieves the values of the data strobe signal from the strobe retrieve unit, and calculates the flight time using the retrieved value, wherein the adjustment unit instructs the valid signal output unit of the timing to output the valid signal, according to an internal clock signal, and calculates the flight time using a phase difference between the internal clock signal and the data strobe signal, wherein the adjustment unit uses a requestor clock signal used by requestor as the internal clock signal, and wherein the data retrieve unit comprises: a mask unit that enables the data strobe signal in accordance with the valid signal, and outputs the enabled signal; a data value retrieve unit that retrieves a data value from the data signal with the signal output from the mask unit; and a delay unit that delays the retrieved data value according to the requestor clock signal.