Graphics Double Data Rate or GDDR memory is a critical component of high-performance devices, especially in the graphics and AI sectors. The latest stage of technology development is GDDR7 memory. Samsung announced at the IEEE International Solid State Circuits Conference in February 2024 “16Gbps, 37Gbps GDDR7 DRAM with PAM3 optimized TRX correction and ZQ calibration.”
The GDDR7 memory that Samsung is preparing is said to enable data transfer rates of up to 37 Gbit/s per pin, which corresponds to a bandwidth of 37 GT/s. That is, the new 16 GB Samsung GDDR7 chip will be able to provide data transfer speeds of up to 148 GB / s, and the memory subsystem of a graphics card from such chips will have throughput in combination with a 384-bit bus of enable 1,776 TB/s. For comparison: the current GeForce RTX 4090 with GDDR6X memory achieves 1,008 TB/s. In addition to higher performance, the Samsung GDDR7 chip uses 20% less energy, according to the manufacturer.
The PAM3 circuit helped achieve such high speeds – pulse amplitude modulation with three signal levels (-1, 0 and +1). This mechanism allows three bits of data to be transmitted in two cycles, which is more efficient than the two-stage NRZ of GDDR6. However, PAM3 signals are more difficult to generate and decode than NRZ signals, resulting in higher power consumption, and they are more susceptible to interference. But PAM3 has other advantages, which is why this circuit is used in GDDR7.
Samsung also mentioned that it used an epoxy compound with 70% higher heat resistance, which is a sign that GDDR7 memory modules run hotter than GDDR6, especially at high clock speeds. The manufacturer promised a GDDR7 version with a lower operating voltage for laptops, but the company did not disclose the performance indicators of the components of this version.
GDDR7 is expected to be available with the next generation of AMD and NVIDIA GPUs later this year.