Semiconductor memory device with delay circuit and sense amplifier circuit

Abstract

A memory cell is provided at an intersection of a word line and a bit line, and a dummy cell is provided at an intersection of a dummy word line and a dummy bit line. A delay circuit delays a signal read into the dummy bit line to generate a sense amplifier activating signal. A sense amplifier circuit starts an operation based on a change in the sense amplifier activating signal, and detects/amplifies a signal read out from the memory cell into the bit line. The delay circuit is configured having a first logical gate circuit and a second logical gate circuit alternately cascade-connected. A second delay time is longer than a first delay time, the second delay time being a time required for an output signal of the second logical gate circuit to switch from a first logical state to a second logical state, and a first delay time being a time required for an output signal of the first logical gate circuit to switch from a first logical state to a second logical state.