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

A semiconductor memory device, comprising:

• 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 unit from which dummy data are read in synchronization with said read pulse using a prescribed potential as reference;
• a delay means for delaying the transition to said prescribed potential in said dummy cell unit until a prescribed timing that follows in time the timing of a prescribed edge of said read pulse having a prescribed pulse width;
• and
• abnormality detection means for generating an error detection signal when the pulse width of said read pulse fluctuates and the transition to said prescribed potential precedes in time the timing of said prescribed edge.

A semiconductor memory device, comprising:

• 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;
• first and second dummy cell units from which dummy data are read in synchronization with said read pulse using a prescribed potential as reference;
• a first delay means for delaying the transition to said prescribed potential in said first dummy cell unit until a prescribed timing that precedes in time the timing of a prescribed edge of said read pulse having a prescribed pulse width;
• a second delay means for delaying the transition to said prescribed potential in said second dummy cell unit until a prescribed timing that follows in time the timing of said prescribed edge of said read pulse;
• a first abnormality detection means for generating an error detection signal when the pulse width of said read pulse fluctuates and the transition to said prescribed potential in said first dummy cell unit follows in time the timing of said prescribed edge;
• and
• second abnormality detection means for generating an error detection signal when the pulse width of said read pulse fluctuates and the transition to said prescribed potential in said second dummy cell unit precedes in time the timing of said prescribed edge.

A method of determining frequency, comprising steps of:

• reading dummy data from a prescribed dummy cell unit in synchronization with a read pulse that is received as input from the outside and using a prescribed potential as reference;
• delaying the transition to said prescribed potential in said prescribed dummy cell unit until a prescribed timing that precedes in time the timing of a prescribed edge of said read pulse having a prescribed pulse width;
• and
• generating an error detection signal when the pulse width of said read pulse fluctuates and the transition to said prescribed potential is completed after the timing of said prescribed edge.

A method of determining frequency, comprising steps of:

• reading dummy data from a prescribed dummy cell unit in synchronization with a read pulse that is received as input from the outside and using a prescribed potential as reference;
• delaying the transition to said prescribed potential in said prescribed dummy cell unit until a prescribed timing that follows in time the timing of a prescribed edge of said read pulse having a prescribed pulse width;
• and
• generating an error detection signal when the pulse width of said read pulse fluctuates and the transition to said prescribed potential is completed before the timing of said prescribed edge.