Jong-Pil Son

64Mb mobile stacked single-crystal Si SRAM (S/sup 3/RAM) with selective dual pumping scheme (SDPS) and multi cell burn-in scheme (MCBS) for high density and low power SRAM

A 64Mb Mobile S/sup 3/RAM was designed with stacked single-crystal thin film transistor (SSTFT) cell using 80nm SRAM technology to overcome chip size penalty of conventional 6T-SRAM with improved performance. For 1.3V operation, word line (WL) and cell Vcc were pumped simultaneously using selective dual pumping scheme (SDPS). Access time of 49.2ns was achieved at 1.3V supply voltage. Multi cell burn-in scheme (MCBS) and standby current (ISB1) repair scheme enhanced the yield for the high density products.

Main Memory in HPC: Do We Need More or Could We Live with Less?

An important aspect of High-Performance Computing (HPC) system design is the choice of main memory capacity. This choice becomes increasingly important now that 3D-stacked memories are entering the market. Compared with conventional Dual In-line Memory Modules (DIMMs), 3D memory chiplets provide better performance and energy efficiency but lower memory capacities. Therefore, the adoption of 3D-stacked memories in the HPC domain depends on whether we can find use cases that require much less memory than is available now. This study analyzes the memory capacity requirements of important HPC benchmarks and applications. We find that the High-Performance Conjugate Gradients (HPCG) benchmark could be an important success story for 3D-stacked memories in HPC, but High-Performance Linpack (HPL) is likely to be constrained by 3D memory capacity. The study also emphasizes that the analysis of memory footprints of production HPC applications is complex and that it requires an understanding of application scalability and target category, i.e., whether the users target capability or capacity computing. The results show that most of the HPC applications under study have per-core memory footprints in the range of hundreds of megabytes, but we also detect applications and use cases that require gigabytes per core. Overall, the study identifies the HPC applications and use cases with memory footprints that could be provided by 3D-stacked memory chiplets, making a first step toward adoption of this novel technology in the HPC domain.