Read zero DRAM

摘要

A dynamic random access memory (DRAM) having a conventional cell layout and having its data access path adapted to access a "zero' faster than a "one.' The DRAM comprising two capacitors coupled respectively to two neighboring word lines. The two capacitors are also coupled respectively to two neighboring bit lines via two pass gates. Data is represented as complementary data bits on the two capacitors. In so doing, a "zero' is ensured to be stored in either one of the two capacitors. A voltage level "zero' is in turn ensured to be maintained on the bit line coupled to the capacitor that stores the "zero' data bit. The sense amplifier and the write driver take advantage of the fact that a voltage level "zero' is ensured to be maintained in either one of the two bit lines. Each of a sense amplifier and a write driver, as parts of the DRAM's data access path, amplifies a "zero' and a "one' unequally by amplifying the "zero' faster than the "one.' Access time is thus improved. The DRAM does not need to operate in the differential sensing mode. The DRAM can operate in either the differential sensing mode or the conventional mode. The switch between the differential and the conventional sensing modes can be implemented without having to alter the cell layout of a conventional DRAM.