DDR SDRAM

Desktop DDR Memory Comparison

DDR SDRAM

Double Data Rate Synchronous Dynamic Random-Access Memory (DDR SDRAM) is a type of synchronous dynamic random-access memory (SDRAM) that improves performance by transferring data on both the rising and falling edges of the clock signal. This effectively doubles the data rate without increasing the clock frequency.

History

DDR SDRAM was introduced in the late 1990s as an improvement over the earlier Single Data Rate SDRAM (SDR SDRAM). The first generation, known as DDR1, was followed by subsequent generations including DDR2 SDRAM, DDR3 SDRAM, and DDR4 SDRAM, each offering improvements in speed, power consumption, and other features.

Technical Specifications

DDR SDRAM operates by using a 2-bit prefetch buffer, which allows it to transfer data twice per clock cycle. This is achieved by using both the rising and falling edges of the clock signal. The memory modules are typically identified by their data transfer rate, such as DDR-200, DDR-266, DDR-333, and DDR-400, which correspond to the effective data rates of 200 MT/s, 266 MT/s, 333 MT/s, and 400 MT/s, respectively.

Voltage

DDR SDRAM typically operates at a voltage of 2.5V, which is lower than the 3.3V used by SDR SDRAM. This reduction in voltage helps to decrease power consumption and heat generation.

Latency

Latency in DDR SDRAM is measured in clock cycles and is denoted by the CAS (Column Address Strobe) latency. Common CAS latencies for DDR SDRAM range from 2 to 3 clock cycles.

Generations

• DDR1 SDRAM: The first generation of DDR SDRAM, offering data rates from 200 MT/s to 400 MT/s.
• DDR2 SDRAM: Improved version with higher data rates, lower power consumption, and enhanced performance.
• DDR3 SDRAM: Further improvements in speed and efficiency, with data rates up to 2133 MT/s.
• DDR4 SDRAM: The latest widely used generation, offering even higher data rates and lower power consumption.

Applications

DDR SDRAM is widely used in personal computers, laptops, servers, and other computing devices. Its ability to provide high-speed data transfer makes it suitable for applications requiring fast memory access, such as gaming, video editing, and scientific computing.

Related Pages

• SDRAM
• DDR2 SDRAM
• DDR3 SDRAM
• DDR4 SDRAM
• Random-access memory
• Computer memory

See Also

• GDDR SDRAM
• LPDDR