Abstract: Nonvolatile evaluation memory cells are programmed to be a plurality of different values in advance, respectively. An internal voltage generating circuit can change the value of an internal voltage according to adjusting signals. To make the internal voltage close to its expected value, a voltage adjusting circuit outputs adjusting signals in accordance with cell currents that flow through the evaluation memory cells, respectively, in a read operation on the evaluation memory cells. As a result, the interval voltage that is shifted from its expected value due to variations in manufacturing conditions can automatically be set to the expected value by using the adjusting signals. Since an internal circuit operates on a correct internal voltage, operation margins can be increased. The yield of a nonvolatile semiconductor memory can thus be increased.

Abstract: A charge loss restoration method detects a memory cell having a tendency of a charge loss within a memory cell array of an electrically writable and erasable nonvolatile semiconductor memory device, using a charge loss detecting reference cell having a threshold value set between a threshold value of a read reference cell and a threshold value of a write verify reference cell, where the threshold value of the write verify reference cell is higher than the threshold value of the read reference cell, and restores the memory cell having the tendency of the charge loss by making an additional write thereto.

Abstract: A charge loss restoration method detects a memory cell having a tendency of a charge loss within a memory cell array of an electrically writable and erasable nonvolatile semiconductor memory device, using a charge loss detecting reference cell having a threshold value set between a threshold value of a read reference cell and a threshold value of a write verify reference cell, where the threshold value of the write verify reference cell is higher than the threshold value of the read reference cell, and restores the memory cell having the tendency of the charge loss by making an additional write thereto.

Abstract: A non-volatile semiconductor memory device includes a memory cell array and an operation control circuit. The memory cell array includes a plurality of non-volatile memory cells that are electrically rewritable. The operation control circuit controls an operation of the memory cell array in accordance with an external instruction. The operation control circuit includes a flag circuit and an erase prohibition circuit. The flag circuit is set when erase incompletion is detected from any of the memory cells by an erase verify operation of the memory cell array. The erase prohibition circuit prohibits an erase operation to the memory cell array irrespective of the external instruction when the flag circuit is in a reset state.

Abstract: A non-volatile semiconductor memory device includes a memory cell array and an operation control circuit. The memory cell array includes a plurality of non-volatile memory cells that are electrically rewritable. The operation control circuit controls an operation of the memory cell array in accordance with an external instruction. The operation control circuit includes a flag circuit and an erase prohibition circuit. The flag circuit is set when erase incompletion is detected from any of the memory cells by an erase verify operation of the memory cell array. The erase prohibition circuit prohibits an erase operation to the memory cell array irrespective of the external instruction when the flag circuit is in a reset state.

Abstract: Nonvolatile evaluation memory cells are programmed to be a plurality of different values in advance, respectively. An internal voltage generating circuit can change the value of an internal voltage according to adjusting signals. To make the internal voltage close to its expected value,- a voltage adjusting circuit outputs adjusting signals in accordance with cell currents that flow through the evaluation memory cells, respectively, in a read operation on the evaluation memory cells. As a result, the interval voltage that is shifted from its expected value due to variations in manufacturing conditions can automatically be set to the expected value by using the adjusting signals. Since an internal circuit operates on a correct internal voltage, operation margins can be increased. The yield of a nonvolatile semiconductor memory can thus be increased.

Abstract: A nonvolatile semiconductor memory device includes a virtual-ground memory array which includes a plurality of nonvolatile memory cells and sub-bit lines connected to the nonvolatile memory cells, first and second selection lines, first and second selection transistors which become conductive in response to activation of the first selection line, a third selection transistor which become conductive in response to activation of the second selection line, a first main bit line which is coupled to and supplies a drain potential to a sub-bit line situated on a drain side of a selected memory cell through the first selection transistor, a second main bit line which is coupled to and supplies a source potential to a sub-bit line situated on a source side of the selected memory cell through one of the second selection transistor and the third selection transistor, and a third main bit line which is coupled to a sub-bit line adjacent to the sub-bit line situated on the drain side of the selected memory cell through a

Abstract: A nonvolatile semiconductor memory device includes a virtual-ground memory array which includes a plurality of nonvolatile memory cells and sub-bit lines connected to the nonvolatile memory cells, first and second selection lines, first and second selection transistors which become conductive in response to activation of the first selection line, a third selection transistor which become conductive in response to activation of the second selection line, a first main bit line which is coupled to and supplies a drain potential to a sub-bit line situated on a drain side of a selected memory cell through the first selection transistor, a second main bit line which is coupled to and supplies a source potential to a sub-bit line situated on a source side of the selected memory cell through one of the second selection transistor and the third selection transistor, and a third main bit line which is coupled to a sub-bit line adjacent to the sub-bit line situated on the drain side of the selected memory cell through a

Abstract: A clock modulator for in-vehicle electronic equipment requiring an EMI countermeasure optimally reduces undesired radiant noise by a low spectral dispersion number. A delay circuit has delay buffers DB0 to DB30 connected in series with each other, each outputting an output pulse delayed from an input pulse by a phase delay time &tgr;, and a selection circuit sequentially selecting an output pulse outputted from each of the delay buffers DB0 to DB30. Adjustment is made such that with respect to an input CLK inputted to the delay buffer DB0, a phase variation amount of the output pulse from the delay buffer DB0 and a phase variation amount of the output pulse from the delay buffer DB30 are near ±45° when a phase of the output pulse from the delay buffer DB15, at a center position of the delay buffers DB0 to DB30, is made a reference.

Abstract: The present invention relates to a clock modulator suitable for use in an in-vehicle electronic equipment requiring an EMI countermeasure, and has an object to provide a clock modulator which can optimally reduce undesired radiant noise by a low spectral dispersion number.