Semiconductor Memories (Yu xiang).ppt

  • 1,745 views
Uploaded on

 

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
    Be the first to like this
No Downloads

Views

Total Views
1,745
On Slideshare
0
From Embeds
0
Number of Embeds
0

Actions

Shares
Downloads
61
Comments
0
Likes
0

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 1. Semiconductor Memories ECE423 Xiang Yu 12.16.06
  • 2. RAM vs. ROM
    • Volatile
    • RAM (random access)
      • SRAM (static)
        • Synchronous
        • Asynchronous
      • DRAM (dynamic)
        • FPM DRAM
        • EDO DRAM
        • SDRAM
        • DDR SDRAM
        • DDR2 SDRAM
        • Etc..
    • Non-volatile
    • ROM (read only)
      • System/Video BIOS
    • PROM
      • OTP with fuses/anti-fuses
    • EPROM
      • UV light for erasure
    • EEPROM
      • Reprogrammable with software and hardware
      •  Flash Memory
  • 3. SRAM & DRAM
    • SRAM
      • Pros
        • Extremely Fast
        • No refresh cycle
      • Cons
        • Large area - 6T/bit
        • Expensive
      • Applications
        • Memory caches L1 & L2
    • DRAM
      • Pros
        • Cheaper
        • Higher density - 1T/bit
      • Cons
        • Slower in speed
        • Needs refresh cycle
      • Applications
        • Computer memory
  • 4. Flash Memory
    • Pros
    • Non-volatile
    • Portability
    • High Density
      • Floating gate transistor
        • CG and FG
        • MLC technology
    • High Isolation
    • Cons
    • Oxide layers near min. limit
    • High voltage required
    • Slow WRITE cycle
    • Capacitance Coupling
    • Limited Use
  • 5. Focus For Improvement
    • Non-volatility
    • Portability
    • Small Area
    • High Density
    • Faster WRITE/ERASE cycles
    • Lower Power
    • Lower Costs
    • Longevity
  • 6. FRAM
    • FeRAM (Ferroelectric RAM)
      • Uses ferroelectric characteristics of the capacitor
        • lead (Pb) zirconate (Zr) titanate (Ti) - PZT
    • Pros
    • Non-volatile
    • Small size
    • Fast WRITE cycles
    • Cons
    • A potential WRITE after each READ
    • Longevity
    • Polarization degradation
    • Requires high temperatures
    • Want higher densities
  • 7. MRAM
    • Magnetoresistive RAM
      • Uses properties of magnetism and the development of the MTJ
      • Uses STT technology (Spin Torque Transfer)
    • Pros
    • Non-volatile
    • Small size
    • Fast WRITE cycles
    • Longevity
    • Cons
    • Requires high temperatures
    • Want higher densities
  • 8. PRAM
    • Phase-change RAM, PCM, C-RAM (chalcogenide RAM)
      • Uses the special property of chalcogenide alloy
        • Germanium (Ge), antimony (Sb) and tellurium (Te) – GST
        • Switches between amorphous (0) and crystallized (1) states with heat from current
    • Pros
    • Non-volatile
    • Small size
    • High density
    • Fast switching times
    • Cons
    • Requires high current (heat)
    • Longevity
  • 9. Comparisons
    • Overall View
    5 ns 5 ns 20 ns 10 μ s 10 ns 2 ns Write Time > 10 12 > 10 15 > 10 12 10 5 > 10 15 > 10 15 Write cycles No No No No ms No Refresh 1T1R 1TCMTJ 1T1C 1T 1T1C 6T Cell Size 10ns Yes MRAM 10ns 10ns 70ns 10 ns 2 ns Read Time Yes Yes Yes No No Non-volatile PRAM FRAM Flash DRAM SRAM Parameters