Semiconductor memory device, data processor, and method of determining frequency

摘要

A semiconductor memory device includes: a plurality of memory cells from which memory data are successively read in synchronization with a read pulse that is received as input from the outside; at least one dummy cell from which dummy data are read in synchronization with the read pulse and a prescribed potential is used as a standard; a variable resistor element for delaying the transition to the prescribed potential in the dummy cell until a prescribed timing that precedes in time the timing of a prescribed edge of the read pulse having a prescribed pulse width, and an error output circuit for generating an error detection signal when the pulse width of the read pulse fluctuates and the transition to the prescribed potential comes after the timing of the prescribed edge.