What is Refresh?

Refresh in the explanations

• Refresh reads and rewrites each cell before its data becomes unreadable; standards typically require every row to be refreshed within 64 ms.

  Why does DRAM need periodic refresh operations?

• In self-refresh mode the DRAM refreshes itself using an internal timer, so the external clock and controller can be stopped, preserving data at low power while a phone or PC sleeps.

  Which correctly describes the self-refresh mode of DRAM?

• As capacity grows, more cells must be refreshed in the same 64 ms, lengthening each refresh operation (tRFC).

  As DRAM capacity grows, what tends to become a problem with…

Questions that mention Refresh (17)

1. Why does DRAM need periodic refresh operations?
2. Which correctly describes the self-refresh mode of DRAM?
3. As DRAM capacity grows, what tends to become a problem with respect to refresh?
4. Which correctly describes the read operation of DRAM?
5. Which correctly describes a property of DRAM?
6. How does the data retention time of DRAM cells generally change as temperature rises?
7. Compared with SRAM, which is a characteristic of DRAM?
8. What is the main use of the DRAM standard called LPDDR?
9. In DRAM, what is the phenomenon in which repeatedly activating one row in a short time can flip data in adjacent rows?
10. Which correctly describes the main leakage paths that determine the data retention time of DRAM cells?
11. In typical DRAM standards, which is closest to the period within which every cell must be refreshed once? (Normal temperature range)
12. Which is closest to the peak bandwidth of one channel of DDR4 memory with a data rate of 3,200 MT/s and a 64-bit data bus?
13. What is commonly required by DRAM standards when the chip temperature is in the high range (for example, above 85 °C)?
14. Some DRAM cells have a data retention time that irregularly switches between longer and shorter values over time. What is this phenomenon called?
15. Which correctly describes the structure of a typical six-transistor SRAM cell?

Related terms

Bank 6T SRAM cell Bit line Sense amplifier 1T1C cell LPDDR Rowhammer GIDL (gate-induced drain leakage) ECC (error-correcting code) CAS latency