Semiconductor memory device
View Patent ↗With the objective of providing a semiconductor memory device which is made identical in usability to a static RAM by use of dynamic memory cells and realizes a high-speed memory cycle time, there is provided a pseudo static RAM having a time multiplex mode which, when instructions for a memory operation for reading memory information from each of memory cells each requiring a refresh operation for periodically holding the memory information, or writing the same therein is issued, carries out an addressing-based autonomous refresh operation different from the memory operation before or after the memory operation. The pseudo static RAM includes address signal transition detectors for a row and a column, and a page mode which independently performs a column address selecting operation according to an address signal transition detect signal of the second address signal transition detector.
1. A semiconductor device, comprising:
a first semiconductor memory device formed on a first semiconductor chip;
a second semiconductor memory device formed on a second semiconductor chip and different from the first semiconductor chip, including:
word lines,
bit lines,
storage circuits coupled to the word lines and the bit lines so that one storage circuit is coupled to one word line and one bit line, wherein the storage circuits store data therein and each storage circuit is configured to require a refresh operation to hold the data stored therein;
a row address decoder configured to receive row address signals and to select one of the word lines in accordance with the row address signals;
a row address transition detector configured to receive the row address signals to detect a transition of the row address signals;
a column address decoder configured to receive column address signals and to select one of the bit lines in accordance with the column address signals;
a column address transition detector configured to receive the column address signals to detect a transition of the column address signals; and
a timer configured to signal the refresh operation to the storage circuits in accordance with data holding capability of the storage circuits, wherein
the column address transition detector signals a page mode operation which selects bit lines continuously to the column address decoder when the row address signals are constant and the column address signals are changed, and
the refresh operation is executed autonomously before or after a memory operation which is a reading operation for outputting the data from the storage circuits or a writing operation for inputting the data to the storage circuits each of which is different from the refresh operation.
2. The semiconductor device according to claim 1 , wherein the first semiconductor memory device is a nonvolatile semiconductor memory device.
3. The semiconductor device according to claim 1 , wherein
the second semiconductor memory device is a pseudo static random access memory, and
the storage circuits are dynamic memory cells.
4. The semiconductor device according to claim 1 , further comprises:
a third semiconductor memory device formed on a third semiconductor chip different from the first semiconductor chip and the second semiconductor chip, wherein the third semiconductor memory device is a static random access memory.
5. The semiconductor device according to claim 1 , further includes a substrate, wherein the first semiconductor memory device and the second semiconductor memory device are stacked over the substrate.
6. The semiconductor device according to claim 4 , further includes a substrate, wherein the first semiconductor memory device and the second semiconductor memory device and the third semiconductor memory device are stacked over the substrate.