Implementing a DDR Memory Interface on FPGA with Xilinx MIG
FPGAs are optimised for massive parallelism, but their on-chip memory resources are limited. Block RAM (BRAM) and UltraRAM (URAM) are fast and easy to use, but they typically provide only a few tens of megabits to a few hundred megabits of capacity. When your application needs gigabytes — high-resolution video frames, machine-learning weight tables, large look-up tables — external DDR memory becomes essential. Why External DDR Memory? Memory Type Location Typical Capacity Bandwidth Access Latency Distributed RAM On-chip (LUT-based) < 1 MB Very high 1 cycle Block RAM (BRAM) On-chip (dedicated) up to ~200 MB High 1–2 cycles UltraRAM (URAM) On-chip (UltraScale+) up to ~500 MB High 2–3 cycles External DDR Off-chip (dedicated chip) 1–16+ GB Medium-High ~50–100 ns For applications such as: ...