Intel White Paper: Implementing High-Speed Memory Solutions Using External Memory Interface

Using External Memory Interfaces to Achieve Efficient High-Speed Memory

Solutions

WP-01169-1.0 White Paper

This white paper describes some of the components involved in an external memory interface. Altera’s portfolio of 28-nm FPGAs was developed to provide both the highest overall bandwidth of 921 Gbps and a highly efficient solution that allows a designer to get the most effective bandwidth possible.

Introduction

Many FPGA-based systems require an external memory interface. This memory interface often serves as a buffer between the external memory data path, which is often faster than the internal FPGA fabric, and the internal FPGA processing blocks. With the advent of transceiver-based FPGAs, the memory interface has become increasingly important. In order to ensure peak system performance, the memory must be able to store up to hundreds of gigabits of data as fast as the transceivers can provide that data to the FPGA. To keep pace, these data streams require a wide and fast memory interface .

Although I/O performance is important, it is not the complete story on bandwidth. The efficiency of the memory controller can be critically important in determining the actual system bandwidth that can be achieved. This “effective” bandwidth is a critical factor in determining the actual performance of a system.

The Memory Interface

Altera’s external memory interface controller consists of three blocks, as shown in Figure 1. The multiported front end allows multiple processes inside the FPGA to share a common bank of memory, the memory controller implements all of the DDR3 command and addressing, and the physical layer interface (PHY) handles the timing on the data path itself. All three blocks are critical to the design and use of the memory interface block.

© 2011 Altera Corporation. Al l rights reserved. ALTERA, ARRIA, CYCLONE, HARDCOPY, MAX, MEGACORE, NIOS, QUARTUS and STRATIX wor ds and logos are trademarks of Altera Corporation and registered in the U.S. Patent and Trademark Office and in other countries. All other words and logos identified as trademarks or service marks are the property of their

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November 2011 Altera Corporation

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