ALTERNATELY-ACTIVATED OPEN BITLINE TECHNIQUE FOR HIGH-DENSITY DRAMS

An effective bitline technique for high density DRAMs is studied. The open-type bitline structure where the bitlines are activated alternately can decrease the bitline noises and the current dissipation in memory cell arrays. In spite of several disadvantages inherent to the open-type bitline structure, this technique is found to get the larger read-out signal than the conventional bitline configurations for the DRAMs of 64 Mb and beyond. The effectiveness is confirmed with the measurement of the test-chips. This technique is expected to be more efficient for DRAMs of higher density, where the contribution of the inter-bitline capacitance is increased.