SRAM and flash memory
Which correctly describes the static noise margin (SNM) that represents the stability of an SRAM cell?
- AThe amount of noise voltage the cell can withstand without flipping its stored state, obtained from the butterfly curve
- BThe current consumption of the cell
- CThe time taken to read the cell
Show answer and explanation
Answer: A. The amount of noise voltage the cell can withstand without flipping its stored state, obtained from the butterfly curve
SNM is given by the side of the largest square that fits inside the butterfly curve formed by overlaying the transfer characteristics of the cell's two inverters. The larger it is, the more noise-resistant the cell and the less likely its data is to flip. During reads, the access transistor reduces the SNM.
- A. Correct. It is the noise margin obtained from the butterfly curve.
- B. Current consumption is a separate characteristic from SNM.
- C. Read time is the access time, not the SNM.