The Double Data Rate Synchronous Dynamic Random Access Memory (DDR SDRAM) Technology

Article contributed by Mr. Hem Chandra Joshi, Assistant Professor, Faculty of Technology and Computer Applications

Single data rate (SDR) SDRAM memory commonly used in computer earlier to 2002. Double data rate (DDR) SDRAM introduced around 2002 and is a modified version of SDR SDRAM. The most significant difference between DDR and SDR is that DDR reads data on both the rising and falling edges of the clock signal twice as fast as an SDR memory module.

A new version of DDR called DDR2 began to appear in mid-2004. DDR2 achieves speeds beyond that of DDR, delivering bandwidth of up to 8.5 GB per second. The memory of DDR2 based systems install in pairs to run in “dual channel mode” which further increase memory throughput.

The memory technology DDR3 began to appear in systems in late 2007. DDR3 is a modified version of DDR2 and operates at lower voltages, thereby low power and transfer data rates up to 12.8 GB per second. DDR3 based systems can address three memory banks.

For higher performance and increased bandwidth, a new version  DDR4 SDRAM has arrived in 2012, DDR4 delivers lower power consumption, higher performance improved data integrity and low power consumption than DDR3L (DDR3 Low Voltage), up to 50 percent increased in performance provides by DDR4 while decreasing the overall power consumption of computing environment. In DDR4 a power savings up to 40 percent represents a significant improvement over previous memory technologies, in addition to optimized performance and low-cost computing DDR4 also provides cyclic redundancy checks (CRC) for improved data reliability and on-chip parity detection.

 The second largest memory chipmaker SK Hynix after Samsung was officially launched the world’s first DDR5 DRAM chip on October 2020, transfer rate of DDR4 is 3200 Mbps while the new DDR5 offers 4800 to 5600 Mbps which is 1.8 times faster than DDR4. Despite the higher transfer rates, the new DRAM chips operating Voltage being lowered from 1.2 volts to 1.1 volts which makes it more energy efficient with allowing for 20 percent less power consumption. The new DDR5 chips are also loaded with error correcting code (ECC) that is capable of correcting DRAM cell’s 1-bit-level errors by itself. Furthermore the reliability of the DDR5 application system increased by 20 times with the help of new technology and allowed a reduction in power consumption and operating costs of data centers.

All motherboards are built to support only one type of memory, the same motherboard in any system cannot mix and match DDR5, DDR4, DDR3, DDR2 , DDR or SDR memory They will not function and will not even fit in the same sockets

The difference among DDR generations

The memory density and speed is increasing significantly with every new version of DDR

REFERENCES

Intel Technology Journal |Volume 17, Issue 1, 2013

Ahmed Shamil Mustafa, Mohammed Jabbar Mohammed and Muthana Najim Abdulleh “Double-Data Rate DDR Memory Review” International Journal of Advanced Engineering and Nano Technology (IJAENT) ISSN: 2347-6389, Volume-2 Issue-2, January 2015