GDDR4 SDRAM

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GDDR4 SDRAM
Graphics Double Data Rate 4 Synchronous Dynamic Random-Access Memory
Type of RAM
Developer JEDEC
Type Synchronous dynamic random-access memory
Generation4th generation
Predecessor GDDR3 SDRAM
Successor GDDR5 SDRAM

GDDR4 SDRAM, an abbreviation for Graphics Double Data Rate 4 Synchronous Dynamic Random-Access Memory, is a type of graphics card memory (SGRAM) specified by the JEDEC Semiconductor Memory Standard. [1] [2] It is a rival medium to Rambus's XDR DRAM. GDDR4 is based on DDR3 SDRAM technology and was intended to replace the DDR2-based GDDR3, but it ended up being replaced by GDDR5 within a year.

Contents

History

Technologies

GDDR4 SDRAM introduced DBI (Data Bus Inversion) and Multi-Preamble to reduce data transmission delay. Prefetch was increased from 4 to 8 bits. The maximum number of memory banks for GDDR4 has been increased to 8. To achieve the same bandwidth as GDDR3 SDRAM, the GDDR4 core runs at half the performance of a GDDR3 core of the same raw bandwidth. Core voltage was decreased to 1.5 V.

Data Bus Inversion adds an additional active-low DBI# pin to the address/command bus and each byte of data. If there are at more than four 0 bits in the data byte, the byte is inverted and the DBI# signal transmitted low. In this way, the number of 0 bits across all nine pins is limited to four. [9] : 9  This reduces power consumption and ground bounce.

On the signaling front, GDDR4 expands the chip I/O buffer to 8 bits per two cycles, allowing for greater sustained bandwidth during burst transmission, but at the expense of significantly increased CAS latency (CL), determined mainly by the double reduced count of the address/command pins and half-clocked DRAM cells, compared to GDDR3. The number of addressing pins was reduced to half that of the GDDR3 core, and were used for power and ground, which also increases latency. Another advantage of GDDR4 is power efficiency: running at 2.4 Gbit/s, it uses 45% less power when compared to GDDR3 chips running at 2.0 Gbit/s.

In Samsung's GDDR4 SDRAM datasheet, it was referred as 'GDDR4 SGRAM', or 'Graphics Double Data Rate version 4 Synchronous Graphics RAM'. However, the essential block write feature is not available, so it is not classified as SGRAM.

Adoption

The video memory manufacturer Qimonda (formerly Infineon Memory Products division) has stated it will "skip" the development of GDDR4, and move directly to GDDR5. [10]

See also

Related Research Articles

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References

  1. ↑ "Standards & Documents Search: sgram". www.jedec.org. Retrieved 9 September 2013.
  2. ↑ "Standards & Documents Search: gddr4". www.jedec.org. Retrieved 9 September 2013.
  3. ↑ "Samsung Electronics Develops Industry's First Ultra-Fast GDDR4 Graphics DRAM". Samsung Semiconductor . Samsung. October 26, 2005. Retrieved 8 July 2019.
  4. ↑ "History: 2000s". SK Hynix . Retrieved 8 July 2019.
  5. ↑ Samsung Develops Ultra-fast Graphics Memory: A More Advanced GDDR4 at Higher Density
  6. ↑ Samsung sends GDDR4 graphics memory into mass production
  7. ↑ "Samsung releases fastest GDDR-4 SGRAM". The Inquirer . Archived from the original on 2007-02-12.{{cite web}}: CS1 maint: unfit URL (link)
  8. ↑ Samsung accelerates graphics memory to 2000 MHz
  9. ↑ Choi, J.S. (2011). DDR4 Mini Workshop (PDF). Server Memory Forum 2011. This presentation is about DDR4 rather than GDDR4, but both use data bus inversion.
  10. ↑ Softpedia report
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