Circuits Assembly Online Magazine - JEDEC Publishes GDDR7 Graphics Memory Standard

ARLINGTON, VA – JEDEC has published JESD239 Graphics Double Data Rate (GDDR7) SGRAM, which offers double the bandwidth over GDDR6, reaching up to 192 GB/s per device, and is poised to meet the escalating demand for more memory bandwidth in graphics, gaming, compute, networking and AI applications.

JESD239 GDDR7 is the first JEDEC standard DRAM to use the Pulse Amplitude Modulation (PAM) interface for high frequency operations. Its PAM3 interface improves the signal to noise ratio (SNR) for high frequency operation while enhancing energy efficiency. By using three levels (+1, 0, -1) to transmit 3 bits over 2-cycles versus the traditional NRZ (non-return-to-zero) interface transmitting 2 bits over 2-cycles, PAM3 offers higher data transmission rate per cycle resulting in improved performance.

Additional advanced features include:

Core independent LFSR (linear-feedback shift register) training patterns with eye masking and error counters to improve training accuracy while reduce training time.
Doubles the number of independent channels doubles from 2 in GDDR6 to 4 in GDDR7.
Support for 16 Gbit to 32 Gbit densities including support for 2-Channel mode to double system capacity.
Address the market need for RAS (Reliability, Availability, Serviceability) by incorporating the latest data integrity features including on die ECC (ODECC) with real time reporting, data poison, Error check and Scrub, and command address parity with command blocking (CAPARBLK).

“JESD239 GDDR7 marks a substantial advancement in high-speed memory design,” said Mian Quddus, JEDEC Board of Directors Chairman. “With the shift to PAM3 signaling, the memory industry has a new path to extend the performance of GDDR devices and drive the ongoing evolution of graphics and various high-performance applications.”

“GDDR7 is the first GDDR that not only focuses on bandwidth but addresses the market needs for RAS by incorporating the latest data integrity features that allow GDDR devices to better service existing markets such as Cloud gaming and compute and extend into new applications such as AI,” said Michael Litt, Chair of the JEDEC GDDR Subcommittee.