User guide

58 www.xilinx.com System Generator for DSP Getting Started Guide
UG639 (v 14.3) October 16, 2012
Chapter 4: Getting Started
Lesson 5 - Using Memories
Block vs. Distributed RAM
Xilinx FPGAs offer two distinct memory options, Block RAM and Distributed RAM. Block RAM uses dedicated, on-
chip, hardware resources and represents the most area-efficient RAM implementation. Block RAMs offer high
performance but due to their fixed location on the chip, may incur slightly larger routing delays. Distributed RAM
uses the lookup tables in the FPGA slices to implement memory and in doing so will subtract from the slices
available for logical operations. Because Distributed RAM can be located anywhere throughout the chip, routing
delays can be minimized and slightly higher performance can be achieved. Distributed RAM is an excellent option
for small FIFOs.