A novel memory circuit, the transparent-refresh DRAM (TReD), is proposed to make a dynamic random-access memory (DRAM) virtually refresh-free, and a test device is successfully fabricated. The TReD uses dual-port dynamic RAM cells, one port of which is assigned for a refresh operation and the other port is assigned for a normal read/write operation. Using the configuration, users of the RAM are freed from a cumbersome refresh control without access-time degradation. The TReD cell size is about 1/2.5 of a 4-transistor SRAM (static RAM) cell, so that it can provide very-high-density RAM macros, which is functionally static. As a dual-port memory, the proposed dual-port DRAM cell size is 1/5 of the dual-port SRAM cell, and is suitable for large-scale dual-port memory macros in ASIC (application-specific integrated circuit) environments.
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