Patent ID: 7085166

Claim:
A semiconductor memory device comprising: a plurality of nonvolatile memory cells arranged at least in one column for storing a plurality of memory states; a first load cell having a specific current-voltage characteristic, connected to the column for generating a read voltage relative to a read current based on the current-voltage characteristic during reading from a nonvolatile memory cell in the column; a reference cell for storing a reference state corresponding to a reference current to determine a memory state stored in the selected nonvolatile memory cell; a second load cell connected in series with the reference cell for generating a voltage based on the reference current; and a programming circuit for generating a reference voltage substantially equal to a voltage obtained from the current-voltage characteristic of the first load cell with respect to the reference current and programming the reference cell so as to equalize the voltage of the second load cell with the reference voltage, thereby to compensate for variations in the first load cell at the time of programming the reference cell, wherein the plurality of the nonvolatile memory cells each include a gate electrode formed on a semiconductor layer via a gate insulating film, a channel region disposed under the gate electrode, diffusion regions disposed on both sides of the channel region and having a conductive type opposite to that of the channel region, and memory functional units formed on both sides of the gate electrode and having a function of retaining charges, each memory functional unit being formed by at least one of an insulating film including an insulator having the function of retaining charge, an insulating film including at least one conductor or semiconductor dot, and an insulating film including a ferroelectric film in which inner charge is polarized by an electric field and in which the polarized state is held. each memory functional unit being formed by at least one of an insulating film including an insulator having the function of retaining charge, an insulating film including at least one conuctor or semiconductor dot, and an insulating film including a ferroelectric film in which inner charge is polarized by an electric field and in which the polarized state is held.