Abstract: A nonvolatile memory device includes one or more reference cell transistors, one or more memory cell transistors, and a current source circuit including three or more field effect transistors that have gates thereof connected together, the three or more field effect transistors including two or more field effect transistors and another field effect transistor, currents flowing through the two or more field effect transistors being combined to flow through the one or more reference cell transistors, and another field effect transistor having a drain thereof connected to one of the one or more memory cell transistors.

Abstract: A semiconductor memory device includes a plurality of memory cell transistors arranged in a matrix and each configured to store data, and a test circuit configured to output to outside the semiconductor memory device an output signal indicative of an amount of test current flowing through a selected one of the plurality of memory cell transistors, wherein the test circuit includes a plurality of reference cell transistors employed to successively produce varying amounts of currents, a comparison circuit configured to successively compare the amount of test current with each of the varying amounts of currents, and a code generating circuit configured to generate a code indicative of a result of the successive comparisons performed by the comparison circuit, wherein the code is output as the output signal.

Abstract: A nonvolatile memory device includes a pair of PMOS transistors, and a control circuit configured to operate in a store mode to apply to a first one of the PMOS transistors potentials that cause an NBTI degradation purposefully and to apply to a second one of the PMOS transistors potentials that cause no NBTI degradation while causing no current to flow between a source node and a drain node of the first one of the PMOS transistors, and to operate in a recall mode to set gate nodes of the PMOS transistors to a common potential to detect a difference in the NBTI degradation between said PMOS transistors.

Abstract: A memory circuit includes a latch having a first node and a second node to store data such that a logic level of the first node is an inverse of a logic level of the second node, a MIS transistor having a gate node, a first source/drain node, and a second source/drain node, the first source/drain node coupled to the first node of the latch, and a control circuit configured to control the gate node and second source/drain node of the MIS transistor in a first operation such that a lingering change is created in transistor characteristics of the MIS transistor in response to the data stored in the latch, wherein the MIS transistor includes a highly-doped substrate layer, a lightly-doped substrate layer disposed on the highly-doped substrate layer, diffusion regions formed in the lightly-doped substrate layer, a gate electrode, sidewalls, and an insulating film.

Abstract: A memory circuit includes a latch having a first node and a second node, a MIS transistor having a gate node, a first source/drain node coupled to the first node of the latch, and a second source/drain node, and a control circuit configured to control the gate node and second source/drain node to make a lingering change in a threshold voltage of the MIS transistor in a first operation and to cause the latch in a second operation to store data responsive to whether a lingering change in the threshold voltage is present, wherein the MIS transistor includes diffusion regions, a gate electrode, and sidewalls, wherein a metallurgical junction of each of the diffusion regions is positioned under the gate electrode, and a lateral boundary of a depletion layer in the diffusion region serving as a drain is positioned under a corresponding one of the sidewalls in the first operation.

Abstract: A memory circuit includes a latch having a first node and a second node to store data such that a logic level of the first node is an inverse of a logic level of the second node, a MIS transistor having a gate node, a first source/drain node, and a second source/drain node, the first source/drain node coupled to the first node of the latch, and a control circuit configured to control the gate node and second source/drain node of the MIS transistor to make an upward lingering change in a threshold voltage of the MIS transistor in a first operation in response to data stored in the latch and to make a downward lingering change in the threshold voltage in a second operation in response to data stored in the latch.

Abstract: A nonvolatile semiconductor memory device includes a latch circuit having two nodes, a nonvolatile memory cell including two MIS transistors, a bit swapping unit configured to provide straight connections between the two nodes and the two MIS transistors during a first operation mode and to provide cross connections between the two nodes and the two MIS transistors during a second operation mode, and a control circuit configured to cause, in one of the first and second operation modes, the nonvolatile memory cell to store the data latched in the latch circuit as an irreversible change of transistor characteristics occurring in a selected one of the two MIS transistors, and further configured to cause, in another one of the first and second operation modes, the latch circuit to detect the data stored in the nonvolatile memory cell.

Abstract: A nonvolatile semiconductor memory device includes a latch circuit including a first inverter and a second inverter cross-coupled to each other, a source node of a MIS transistor of the first inverter and a source node of a MIS transistor of the second inverter being both coupled to a plate line, and a control circuit configured to apply a first potential to the plate line in a store mode to cause a change in threshold voltage to one of the MIS transistors, and configured to apply a second potential to the plate line in a power-on mode to cause the latch circuit to latch data responsive to the change in threshold voltage generated in the store mode, such that the data latched by the latch circuit in the power-on mode is automatically output to outside the nonvolatile semiconductor memory device upon power-on thereof.

Abstract: A nonvolatile semiconductor memory device includes a latch circuit including a first inverter and a second inverter cross-coupled to each other, a source node of a MIS transistor of the first inverter and a source node of a MIS transistor of the second inverter being both coupled to a plate line, and a control circuit configured to apply a first potential to the plate line in a store mode to cause a change in threshold voltage to one of the MIS transistors, and configured to apply a second potential to the plate line in a power-on mode to cause the latch circuit to latch data responsive to the change in threshold voltage generated in the store mode, such that the data latched by the latch circuit in the power-on mode is automatically output to outside the nonvolatile semiconductor memory device upon power-on thereof.

Abstract: A nonvolatile semiconductor memory device includes a latch configured to store data, a plurality of word lines, a driver configured to activate one of the plurality of word lines, and a plurality of nonvolatile memory cells coupled to the respective word lines, each of the nonvolatile memory cells coupled to the latch so as to exchange stored data with the latch upon activation of a corresponding one of the word lines, each of the nonvolatile memory cells including two MIS transistors and configured to store data as an irreversible change of transistor characteristics occurring in one of the two MIS transistors, wherein the driver includes at least one nonvolatile memory cell storing count data responsive to a number of times storing of data has been performed with respect to the plurality of nonvolatile memory cells, and is configured to activate one of the word lines indicated by the count data.

Abstract: A nonvolatile semiconductor memory device includes a nonvolatile memory cell including an odd number of MIS transistor pairs, each of which stores one-bit data by creating an irreversible change of transistor characteristics in one of the two paired MIS transistors, latches equal in number to the odd number of MIS transistor pairs to store the odd number of one-bit data recalled from the MIS transistor pairs, the recalling of the one-bit data of a given MIS transistor pair being performed by sensing a difference in the transistor characteristics between the two paired MIS transistors of the given MIS transistor pair, and a majority decision circuit configured to make a majority decision based on the odd number of one-bit data to determine a bit value of the nonvolatile memory cell.

Abstract: A nonvolatile semiconductor memory device includes a first latch to store data, a nonvolatile memory cell including two MIS transistors to store data as an irreversible change of transistor characteristics occurring in one of the two MIS transistors selected in response to the data stored in the first latch, a second latch to store data obtained by sensing a difference in the transistor characteristics between the two MIS transistors, a logic circuit to produce a signal indicative of comparison between the data of the first latch and the data of the second latch, and a control circuit configured to repeat a store operation storing data in the nonvolatile memory cell, a recall operation storing data in the second latch, and a verify operation producing the signal indicative of comparison until the signal indicates that the data of the first latch and the data of the second latch are the same.

Abstract: A nonvolatile semiconductor memory device includes a control circuit, an inverting circuit, and memory units, each of the memory units including a latch having a first node and a second node, a plate line, a first MIS transistor having one of source/drain nodes coupled to the first node of the latch, another one of the source/drain nodes coupled to the plate line, and a gate node coupled to a word line, and a second MIS transistor having one of source/drain nodes coupled to the second node of the latch, another one of the source/drain nodes coupled to the plate line, and a gate node coupled to the word line, wherein the control circuit is configured to invert the data latched in the latch by reading the data from the latch, causing the inverting circuit to invert the read data, and writing the inverted data to the latch.

Abstract: A nonvolatile semiconductor memory device includes a data input buffer configured to receive data from outside the device, a nonvolatile memory cell including two MIS transistors to store first data received by the data input buffer by creating an irreversible change of transistor characteristics in one of the two MIS transistors, whichever is selected in response to a value of the first data, a sense latch coupled to the nonvolatile memory cell and configured to store the first data obtained by sensing a difference in the transistor characteristics between the two MIS transistors of the nonvolatile memory cell, and a logic circuit configured to produce a signal indicative of comparison between the first data stored in the sense latch and second data received by the data input buffer, wherein no data path to output the first data stored in the sense latch to outside the nonvolatile semiconductor memory device exists.

Abstract: A nonvolatile semiconductor memory device includes a plurality of control lines, a control circuit configured to assert selected ones of the control lines, and a plurality of memory cell arranged in rows and columns and including respective latch circuits and respective nonvolatile memory cells, wherein the memory cell units are configured to perform a write operation in which the latch circuits of the memory cell units on a selected row store respective bits of the input data, and are further configured to perform a store operation in which the respective bits of the input data are transferred from the latch circuits to the nonvolatile memory cells for storage therein in response to assertion of respective control lines by the control circuit, so that only one or more selective bits of the input data selected by the control circuit are stored in the nonvolatile memory cells.

Abstract: A nonvolatile semiconductor memory device includes a memory cell having a MIS transistor configured to experience an irreversible change in transistor characteristics thereof to store data as the irreversible change, the MIS transistor having a gate node coupled to a word selecting line and a source/drain node coupled to a bit line, and the MIS transistor becoming conductive in response to a first state of the word selecting line and becoming nonconductive in response to a second state of the word selecting line, and a test circuit coupled to the bit line to sense a current running through the MIS transistor, the test circuit configured to indicate error in response to either a detection of presence of the current when the word selecting line is in the second state or a detection of absence of the current when the word selecting line is in the first state.

Abstract: A memory circuit includes a latch having a first node and a second node, a first MIS transistor operable to couple between the first node and a predetermined node, a second MIS transistor operable to couple between the second node and the predetermined node, and a control circuit configured to subject one of the first MIS transistor and the second MIS transistor to bias conditions that cause a lingering change in transistor characteristics thereof, wherein the MIS transistors of the latch have a lightly-doped-drain structure that includes first diffusion regions having a first impurity concentration and second diffusion regions having a second impurity concentration smaller than the first impurity concentration, and each of the first MIS transistor and the second MIS transistor has a doped diffusion region closest to a conduction channel with an impurity concentration different from the second impurity concentration.

Abstract: A nonvolatile memory circuit includes a flip-flop to degrade an internal circuit irreversibly based on a voltage applied to a first or second bit line so as to latch data in a nonvolatile manner, a first switch coupled between a first output terminal of the flip-flop and the first bit line, a second switch coupled between the first output terminal of the flip-flop and the first bit line, a third switch coupled between a second output terminal of the flip-flop outputting an inverse of an output of the first output terminal and the second bit line, and a fourth switch coupled between the second output terminal of the flip-flop and the second bit line.

Abstract: A nonvolatile semiconductor memory circuit includes a selection line, a first bit line, a second bit line, a first MIS transistor having a first gate coupled to the selection line, a first drain coupled to the first bit line via a first node, and a first source coupled to a predetermined potential, a second MIS transistor having a second gate coupled to the selection line, a second drain coupled to the second bit line via a second node, and a second source coupled to the predetermined potential, and a latch circuit coupled to the first node and the second node to store data responsive to a signal difference between the first node and the second node, wherein the selection line is operative to supply a write potential that creates a lingering change in a threshold voltage of one of the first MIS transistor and the second MIS transistor.

Abstract: A memory circuit includes a latch having a first node and a second node, a plate line, a word selecting line, a first MIS transistor having source/drain nodes thereof coupled to the first node and the plate line, respectively, and a gate node thereof coupled to the word selecting line, a second MIS transistor having source/drain nodes thereof coupled to the second node and the plate line, respectively, and a gate node thereof coupled to the word selecting line, and a driver configured to set the plate line to a first potential causing a current to flow in a first direction through the first MIS transistor in a first operation mode and to a second potential causing a current to flow in a second direction through the first MIS transistor in a second operation mode, the first operation mode causing a lingering change in characteristics of the first MIS transistor.