sram chip
2017-12-07 14:25:16
Static random access memory (
SRAM) is a form of memory in a computer system. SRAM provides lowlatency, high speed data access. It is a volatile memory technology, meaning that its data is lost when power is turned off. Because of the relatively large SRAM cell size, it is not economically feasible to implement large capacity memories as SRAM.
Historically, SRAM provided memory to the computer system in discrete form. That role has since been supplanted by DRAM. However, SRAM continues to play a very important role integrated into silicon alongside CPUs, ASICs, and SoCs. Processor cache is almost exclusively implemented as SRAM. Firmware registers and FIFOs within the digital logic also utilize SRAM.
The core of a singlebit SRAM cell is just a latch made of two crosscoupled inverters. There are also two transistors, which act as pass gates to control access to the cell from the bitline. The feedback loop inherent in the latch means that periodic refresh cycles (such as in DRAM) are unnecessary. To read from the SRAM cell, the pass gates are activated and the latch is allowed to drive the bitlines high or low. Writing to the SRAM cell is more involved: the internal feedback of the latch must be overpowered by the input circuit, which is providing the new data.
