Asynchronous DRAM design and synthesis

We present the design of a high performance on-chip pipelined asynchronous DRAM suitable for use in a microprocessor cache. Although traditional DRAM structures suffer from long access latency and even longer cycle times, our design achieves a simulated core sub-nanosecond latency and a respectable cycle time of 4.8 ns in a standard 0.25 μm logic process. We also show how the cycle time penalty can be overcome by using pipelined interleaved banks with quasi-delay insensitive asynchronous control circuits. We can thus approach the performance of SRAM, which is typically used for caches, while still benefiting from the smaller area footprint of DRAM.