Synchronous dynamic random-access memory
AssigneeNEC Corporation
InventorTaketo Maesako
Life of this patent
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Abstract
The present invention provides a double data rate synchronous dynamic random-access memory (SDRAM) which allows a data mask signal to mask a data signal on a bit basis during write operation at a low frequency while maintaining compatibility with conventional SDRAMs and which increases the margin of the DRAM and the overall system. The double data rate synchronous dynamic random-access memory has address signal lines over which an unused column address signal is sent to a byte mask data latch circuit for use as the mask signal.
Claims10
A double data rate synchronous dynamic random-access memory comprising:
- an address signal line over which an unused column address signal is sent to a byte mask data latch circuit to form a mask signal.
A double data rate synchronous dynamic random-access memory comprising:
- an address signal line over which an unused column address signal is sent to a byte mask data latch circuit, wherein said column address signal is allocated for a rising edge or a falling edge of a data strobe signal to form a mask signal of a data signal to allow data to be masked on a bit basis during writing.
A double data rate synchronous dynamic random-access memory having a multiple-bank memory cell array driven in synchronization with a first clock, said synchronous dynamic random-access memory comprising:
- an input/output buffer to or from which data signals of the synchronous dynamic random-access memory are input or output in response to a second clock synchronizing with said first clock;
- a latch circuit which performs an input/output of the data signals between the input/output buffer and the memory cell array;
- and
- a byte mask data latch circuit which allocates an unused column address signal to the latch circuit for use when said data strobe signal rises or falls for outputting a mask signal;
- wherein said mask signal write-masks the data signals.
Dependencies are inferred from the claim text.