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Semiconductor Memories

Semiconductor Memories. Introduction. Semiconductor memory  is an electronic data storage device, often used as computer memory, implemented on a  semiconductor-based integrated circuit. Semiconductor memory. Example of Semiconductor memory.

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Semiconductor Memories

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  1. Semiconductor Memories

  2. Introduction • Semiconductor memory is an electronic data storage device, often used as computer memory, implemented on a semiconductor-based integrated circuit.

  3. Semiconductor memory

  4. Example of Semiconductor memory • Examples of semiconductor memory includes Non-volatile memory such as Read-only memory (ROM), Magnetoresistive Random Access Memory (MRAM), and Flash memory. • It also includes volatile memory such as Static Random Access Memory (SRAM)

  5. Cont., • These memories can be constructed to store large amount of data entirely within a computer system. • The number of locations and the size of storing data may vary from memory to memory. • Each location is called Memory cell.

  6. Memory cell operation

  7. Memory cell • The memory cell is used to store single bit of information. • The memory cell is fabricated by using either bipolar Metal Oxide Semiconductors (MOS) or Complementary Metal Oxide Semiconductors(CMOS).

  8. Semiconductor memory classification

  9. Memory Architecture: Decoders

  10. Array-Structured memory Architecture

  11. Hierarchical memory Architecture

  12. Memory Timing Definitions

  13. Memory Timing Approaches

  14. Read-Write Memories (RAM) Static (SRAM) • Data stored as long as supply is applied • Large (6 transistor/cell) • Fast • Differential

  15. Read-Write Memories Dynamic (DRAM) • Periodic refresh required • Small (1-3 transistors/cell) • Slower • Single Ended

  16. 6- Transistor CMOS SRAM Cell

  17. CMOS SRAM Analysis (Write)

  18. CMOS SRAM Analysis (Read)

  19. 6T- SRAM - Layout VDD M2 M4 Q Q M1 M3 GND M5 M6 WL BL BL

  20. 3- Transistor DRAM Cell

  21. 3-T DRAM Layout BL2 BL1 GND RWL M3 M2 WWL M1

  22. DRAM Cell • 1T DRAM requires a sense amplifier for each bit line, due to charge redistribution read-out. • DRAM Memory cells are single ended in contrast to SRAM cells.

  23. 1-T DRAM cell

  24. Semiconductor Memory Trends Memory Size as a function of time: x 4 every three years

  25. Semiconductor Memory Trends Increasing die size factor 1.5 per generation Combined with reducing cell size factor 2.6 per generation

  26. Semiconductor Memory Trends Technology feature size for different SRAM generations

  27. The End ……. Thank You …….

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