A memory device and a method for test reading and writing thereof are provided. A precharge voltage control circuit is based on the precharge reference voltage to provide a first precharge voltage and a second precharge voltage. A sense amplifier circuit is coupled between a bit line and a complementary bit line and configured to sense data of a memory cell coupled to the bit line, and also coupled to the precharge voltage control circuit to make the bit line and the complementary bit line receive the first precharge voltage and the second precharge voltage respectively, the first precharge voltage and the second precharge voltage are on the same voltage level during the precharge operation, but during a test write sensing period and a test read sensing period after the precharge operation, the voltage levels of the first precharge voltage and the second precharge voltage are different.

A flash memory comprising a first plurality of memory cells, each memory cell of the first plurality of memory cells selectively connected to a first input of a comparator. A second plurality of memory cells selectively connected to a second input of the comparator, wherein a first number of the second plurality of memory cells are in an erased state, wherein a second number of the second plurality of memory cells are in a written state, wherein each memory cell of the first plurality of memory cells and each memory cell of the second plurality of memory cells has a first cell capacitance, and wherein the sum of the first number and the second number is at least three.

A flash memory comprising a first plurality of memory cells, each memory cell of the first plurality of memory cells selectively connected to a first input of a comparator. A second plurality of memory cells selectively connected to a second input of the comparator, wherein a first number of the second plurality of memory cells are in an erased state, wherein a second number of the second plurality of memory cells are in a written state, wherein each memory cell of the first plurality of memory cells and each memory cell of the second plurality of memory cells has a first cell capacitance, and wherein the sum of the first number and the second number is at least three.

Provided is a semiconductor storage apparatus having a storage apparatus driving circuit which can efficiently perform screening tests for the semiconductor memory device. A semiconductor memory device includes a wright-voltage supply circuit, a wright-voltage switching circuit, a bit line discharge control circuit, a bit line discharge circuit, and a memory array. The wright-voltage supply circuit is connected to the memory array through the wright-voltage switching circuit. The bit line discharge control circuit is connected to the memory array through the bit line discharge circuit.

Provided is a semiconductor storage apparatus having a storage apparatus driving circuit which can efficiently perform screening tests for the semiconductor memory device. A semiconductor memory device includes a wright-voltage supply circuit, a wright-voltage switching circuit, a bit line discharge control circuit, a bit line discharge circuit, and a memory array. The wright-voltage supply circuit is connected to the memory array through the wright-voltage switching circuit. The bit line discharge control circuit is connected to the memory array through the bit line discharge circuit.

A method of testing a memory device, a memory built-in self-test (MBIST) circuit, and a memory device for improving reliability and reducing a test time. The memory device includes a plurality of memory banks and the MBIST circuit. The MBIST circuit is configured to generate double data rate (DDR) test patterns and parallel bit test (PBT) test patterns to test the memory banks. When a defective cell is detected as a result of the PBT test or the DDR test, the MBIST circuit is configured to perform a repair operation for replacing the defective cell with a redundancy cell and perform a re-test to verify the repair operation. The MBIST circuit may be configured to perform the DDR test on one or more memory cells including the defective cell during the re-test.

A memory circuit may include a plurality of electrically programmable memory cells arranged in an electrically programmable non-volatile memory cell array along a plurality of rows and a plurality of columns, a plurality of word lines, each word line coupled with a plurality of word portions of the plurality of memory cells, each word portion configured to store a data word, and at least one overlay word line coupled with a plurality of overlay portions, each overlay portion including overlay memory cells, each of the plurality of overlay portions including an overlay word. The memory circuit is configured to read, for each of the plurality of word lines, from each of the word portions simultaneously with an overlay portion of the plurality of overlay portions, with an output of the read operation being a result of a logic operation performed on the data word and the overlay word.

A memory circuit may include a plurality of electrically programmable memory cells arranged in an electrically programmable non-volatile memory cell array along a plurality of rows and a plurality of columns, a plurality of word lines, each word line coupled with a plurality of word portions of the plurality of memory cells, each word portion configured to store a data word, and at least one overlay word line coupled with a plurality of overlay portions, each overlay portion including overlay memory cells, each of the plurality of overlay portions including an overlay word. The memory circuit is configured to read, for each of the plurality of word lines, from each of the word portions simultaneously with an overlay portion of the plurality of overlay portions, with an output of the read operation being a result of a logic operation performed on the data word and the overlay word.

A sequence of contiguous pages in an erase block in a non-volatile memory device is programmed and erased. Next, all of the pages in the erase block are programmed with data. Then, the data is read back and verified to determine whether there is an error in the data. When there is an error in the data, then the last page in the sequence is identified as being unstable. If there is no error in the data, then the last page in that sequence is identified as being stable. Thus, the recorded information identifies a point of instability in the erase block. Instabilities can be stabilized by performing additional writes to fill the partially filled word line.

A sequence of contiguous pages in an erase block in a non-volatile memory device is programmed and erased. Next, all of the pages in the erase block are programmed with data. Then, the data is read back and verified to determine whether there is an error in the data. When there is an error in the data, then the last page in the sequence is identified as being unstable. If there is no error in the data, then the last page in that sequence is identified as being stable. Thus, the recorded information identifies a point of instability in the erase block. Instabilities can be stabilized by performing additional writes to fill the partially filled word line.