An output structure for a bi-modal 6.4-Gbps GDDR5 and 2.4-Gbps DDR3 compatible memory interface

A bi-modal x32 memory interface supports 6.4-Gbps GDDR5 signaling as well as 2.4-Gbps DDR3 signaling with a 1.5V IO supply. The interface incorporates a novel driver and pre-driver structure that supports one-tap equalization and presents very small capacitive loading to the pins. The entire interface, including both data and request channels achieves 11.6mW/Gbps and 27.7mW/Gbps energy efficiencies in GDDR5 and DDR3 modes respectively, and communicates successfully with 1.6-Gbps DDR3 and 6.0-Gbps GDDR5 DRAMs.