Abstract: A memory device includes a data array, a parity array and an ECC circuit. The ECC circuit is coupled to the data array and the parity array. In a first test mode, the ECC function of the ECC circuit is disabled, and in a second test mode, the ECC circuit directly accesses the parity array to read or write parity information through the parity array.

Abstract: A semiconductor memory device includes a buffer die and a plurality of memory dies. Each of the memory dies includes a memory cell array, an error correction code (ECC) engine and a test circuit. The memory cell array includes a plurality of memory cell rows, each including a plurality of volatile memory cells. The test circuit, in a test mode, generates a test syndrome and an expected decoding status flag indicating error status of the test syndrome, receives test parity data generated by the ECC engine based on the test syndrome and a decoding status flag indicating error status of the test parity data, and determines whether the ECC engine has a defect based on comparison of the test syndrome and the test parity data and a comparison of the expected decoding status flag and the decoding status flag.

Abstract: A semiconductor memory device according to an aspect of the present invention includes a memory cell array that includes a ferroelectric capacitor and a selection transistor that selects a column of the memory cell array and connects the selected column to a bit line. A plate line applies a potential for reading or writing data to the ferroelectric capacitor. A sense amplifier circuit compares and amplifies a signal read from the ferroelectric capacitor to the bit line. A plate line control circuit controls a potential of the plate line synchronously with a clock signal.

Abstract: The data memory cell array and parity memory cell array in the memory cell array has a constitution that is capable of corresponding with a plurality of ECC code lengths. An input-side parity generation circuit that generates parities from write data, an output-side parity generation circuit that generates parities from read data, and a syndrome generation circuit that generates a syndrome bit that indicates an error bit from the read parity bits and generated parity bits are constituted so as to be capable of switching, according to the plurality of ECC code lengths.