GDDR, or Graphics Double Data Rate memory (originally known as DDR SGRAM – double data rate synchronous graphics RAM), is a crucial component of high-performance devices, especially in the graphics and AI sectors.
The latest development in this technology is GDDR7, which Samsung first teased at Tech Day 2022, and while specific details were initially scarce, more information has since come to light about the promising new memory standard.
On the five-day 2024 IEEE International Solid-State Circuit Conference, to be held in San Francisco in February, GDDR7 will appear in the session on High-Density Memory and Interfaces. There’s not much to go on at the moment other than the session headline in the Advance program: “A 16Gb 37 Gb/s GDDR7 DRAM with PAM3-optimized TRX equalization and ZQ calibration”.
Samsung GDDR7
GDDR7 memory will use PAM3 and NRZ signaling, aiming to achieve data speeds of up to 37 Gbps per pin. Its evolution has led to increasing signal speeds and burst sizes without significantly increasing the internal clocks of the memory cells. This allowed each GDDR version to improve the memory bus frequency, improving performance.
However, as frequency increases become more complex, the industry is exploring other solutions. For example, GDDR6X replaced traditional NRZ encoding with PAM4 encoding, effectively doubling the data transfer speed. With its lower baud rate, PAM4 also significantly reduces signal losses.
However, GDDR7 will use PAM3 encoding, a compromise between PAM4 and NRZ signaling. This enables higher data transmission rates per cycle than NRZ, reducing the need for higher memory bus frequencies. GDDR7 promises better performance than GDDR6, along with lower power consumption and lower implementation costs than GDDR6X.
Additionally, GDDR7 provides ways to optimize memory efficiency and power consumption. This includes four different read clock modes, allowing it to run only when necessary. GDDR7 memory subsystems can also execute two independent commands in parallel, optimizing power consumption.
As for release, it is expected that GDDR7 will likely be available later this year, along with the next generation of GPUs from AMD and NVIDIA.