An 8-Gb GDDR6X DRAM Achieving 22 Gb/s/pin With Single-Ended PAM-4 Signaling

Demand for dynamic random access memory (DRAM) bandwidth has outpaced DRAM transistor performance. Given the options of major process investment to scale beyond sixth-generation graphics double-data-rate (GDDR6) or replace GDDR6 with costly high bandwidth memory (HBM), this article presents a solution that simultaneously increases pin and energy efficiency through the integration of four-level pulse amplitude modulation (PAM-4) into the single-ended memory interface. Building upon the existing GDDR6 architecture, evolutionary modifications to input, output, clocking, and data path, along with the component package design, enable a per-pin data rate of more than 22 Gb/s.