SRAMs and DRAMs With Separate Read–Write Ports Augmented by Phase Transition Materials

Abstract

We propose SRAMs and DRAM with independent read–write paths employing phase transition material (PTM) in the read port to enable a more compact design compared to standardmultiport cells. Our technique employs 1) the orders of magnitude difference in the resistances of the insulating and metallic phases of the PTM and 2) regulated phase transitions to design a 7T single-ended SRAM, an 8T differential SRAM, and a 2T DRAM. Compared to previously proposed 8T SRAM, our 7T design achieves 9.1% less cell area and our 8T design achieves differential read without area penalty. We extensively analyze the material requirements for PTM to enable the proposed cell operation. We show that the read performance of the proposed 7T cell is only 5% worse than previously proposed standard 8T, while the proposed 8T design shows a 38% improvement. Similarly, our 2TDRAM cell achieves 20% less cell area than 3T DRAM, with less than 6% read time penalty. The benefits for all the designs come at no write overheads.