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.
GDDR7 SDRAM employs PAM-3 signaling (three-level pulse-amplitude modulation) rather than NRZ. PAM-3 is 20% more energy-efficient than NRZ while running at a higher bandwidth. Manufacturing equipment will be less costly than PAM-4. PAM-3 processes 1.58 bits per cycle, while NRZ processes only 1 bit per cycle. GDDR7 SDRAM also will be manufactured using 1ß node (equivalent to 12–10 nm process node), which will be the last DRAM production process that will rely on deep ultraviolet (DUV) lithography tools; future devices will be produced using extreme ultraviolet lithography (EUV).
GDDR7 adds on-die error correction code, error checking and scrubbing features for chip reliability, mainly useful for compute/AI use cases.
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, and chip capacities up to 64 Gbit - compared to GDDR6X's 16 Gbit.
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