GDDR7 SDRAM

This article is about DDR graphics RAM (SGRAM). For non-graphics (dynamic) DDR memory, see SDRAM.

GDDR7 SDRAM
Graphics Double Data Rate 7 Synchronous Dynamic Random-Access Memory

Type of RAM
PCB of the NVIDIA GeForce RTX 5090D with sixteen GDDR7 chips (16 Gibibit each)
Developer	JEDEC
Type	Synchronous dynamic random-access memory
Generation	7th generation
Release date	5 March 2024
Predecessor	GDDR6 SDRAM

Graphics Double Data Rate 7 Synchronous Dynamic Random-Access Memory (GDDR7 SDRAM) is a type of synchronous graphics random-access memory (SGRAM) specified by the JEDEC Semiconductor Memory Standard, with a high bandwidth, "double data rate" interface, designed for use in graphics cards, game consoles, and high-performance computing. It is a type of GDDR SDRAM (graphics DDR SDRAM), and is the successor to GDDR6.

History

• At Samsung Tech Day 2022, Samsung announced GDDR7 as the successor of GDDR6X, which could deliver up to 36 GT/s. ^[1] Samsung announced two months later that it would use PAM-3 signaling to achieve the highest transfer rate. ^[2]
• On March 8, 2023, Cadence announced the verification solution tool for preliminary GDDR7 SDRAM production. ^[3]
• On June 30, 2023, Micron announced that it will be manufactured using 1β node (equivalent to 12–10 nm process node), slated to release in H1 2024. ^[4]
• On July 18, 2023, Samsung announced the first generation of GDDR7, which can reach up to 32 Gbps per pin (100% higher bandwidth per pin compared to 16 Gbps per pin on GDDR6), 40% higher bandwidth (1.5 TB/s) compared to GDDR6 (1.1 TB/s) and 20% more energy efficient. For packaging material, it will use epoxy molding compound (EMC) along with IC architecture optimization, which will reduce thermal resistance by 70%. ^[5] Later, on a Q&A session, Samsung mentioned that it will be manufactured using D1z node (equivalent to 15–14 nm ^[6] ) and will operate on 1.2V. A 1.1V version with reduced clockspeeds will also be made available at some point in to the future after the release of the 1.2V version. ^[7]
• On March 5, 2024, JEDEC published the GDDR7 Graphics Memory formal standard and specifications. ^[8]

Technologies

GDDR7 SDRAM employs three-level (-1, 0, +1) pulse-amplitude modulation (PAM-3) instead of NRZ in GDDR6 and PAM-4 in GDDR6x. PAM-3 enables the transfer of three bits of data within two cycles, while NRZ transfer of one bits of data within one cycle. PAM-3 is 20% more energy-efficient than NRZ while running at a higher bandwidth. Manufacturing equipment will be less costly than PAM-4. ^[9]

GDDR7 adds on-die error correction code, error checking and scrubbing features for chip reliability, mainly useful for compute/AI use cases. ^[10]

Initial data rates are at 32 Gbps/pin, while memory manufacturers have noted that rates up to 36 Gbps/pin are readily attainable. The standard has future bandwidth up to 48 Gbps/pin, ^[11] and chip capacities up to 64 Gbit - compared to GDDR6X's 16 Gbit. ^[10]

See also

• List of interface bit rates

References

1. "Samsung announces 36 Gbps GDDR7 memory standard, aims to release V-NAND storage solutions with 1000 layers by 2030". Notebookcheck. 2022-10-06. Retrieved 2023-06-30.
2. Discuss, btarunr (2022-12-05). "Samsung Reveals GDDR7 Memory Uses PAM3 Signalling to Achieve 36 Gbps Data-Rate". TechPowerUp. Retrieved 2023-06-30.
3. "Cadence announces first GDDR7 verification solution". VideoCardz.com. Retrieved 2023-06-30.
4. "Micron could introduce GDDR7 memory chips in early 2024". TechSpot. 2023-06-30. Retrieved 2023-06-30.
5. "Samsung develops industry's first GDDR7 DRAM with 1.5 TBps bandwidth". Notebookcheck. 2023-07-19. Retrieved 2023-07-31.
6. Memory Technology 2021: Trends & Challenges (PDF), 2021, retrieved 2023-07-31
7. Smith, Ryan. "Samsung Completes Initial GDDR7 Development: First Parts to Reach Up to 32Gbps/pin". www.anandtech.com. Retrieved 2023-07-31.
8. "JEDEC Publishes GDDR7 Graphics Memory Standard | JEDEC". www.jedec.org. Retrieved 2024-03-05.
9. Anton Shilov (2023-07-19). "GDDR7 Arrives: Samsung Outs World's First Chip, 32 GT/s for Next-Gen GPUs". Tom's Hardware . Retrieved 2023-10-06.
10. Shilov, Anton. "Micron's GDDR7 Chip Smiles for the Camera as Micron Aims to Seize Larger Share of HBM Market". www.anandtech.com. Retrieved 2024-06-09.
11. Smith, Anton Shilov, Ryan. "JEDEC Publishes GDDR7 Memory Spec: Next-Gen Graphics Memory Adds Faster PAM3 Signaling & On-Die ECC". www.anandtech.com. Retrieved 2024-06-09.