Embedded Memory in Stratix® Series FPGAs

The Stratix® family of FPGAs introduced the concept of TriMatrix memory. In TriMatrix memory, the on-chip memory is implemented in three types of different block sizes, each for a specific use. The memory type has been maintained and optimized through the Stratix series devices.
With significant architectural changes to the internal memory in Stratix® V FPGAs, we've significantly increased both the capacity and bandwidth of these structures. Stratix V FPGAs utilize two types of memory: enhanced memory logic array blocks (MLABs) and M20K memory blocks. These changes have enhanced performance and utilization, improving capabilities for digital signal processing (DSP) designs. Quartus® II software automatically migrates designs from previous Stratix series FPGA memory architectures to the new structure.
Key enhanced MLAB features improve efficiency and bandwidth:

  • Address and data registers internal to MLAB
  • Increased performance
  • Reduced logic use
  • Increased efficiency for wide, shallow FIFOs (n bits wide, 32 or 64 deep)

Key M20K memory block features enhance performance and utilization:

  • Increased embedded memory bit counts
  • Increased memory block performance
  • Improved flexibility of memory architecture to span applications
  • Simplified floorplanning and routability
  • Optional hard error correction code (ECC) protection, which can operate in pipelined or non-pipelined modes

Quartus® II software selects the best-fit memory for each instantiation to provide the most efficient embedded memory implementation.
Table 1 summarizes the differences in the memory blocks and related applications between recent Stratix FPGA families.

Table 1. Comparison Between TriMatrix Blocks in Stratix® III, Stratix® IV, and Stratix® V FPGAs

Memory Functions

Stratix III/IV

Stratix V

  • Processor code storage
  • Packet buffers
  • Video frame buffers


  • General-purpose memory


  • Shift registers
  • Wide shallow FIFO buffers
  • Filter delay lines

144K bits


20K bits


Enhanced MLAB
640 bits

9K bits

640 bits

For full details on memory block capacity for Stratix® V devices, see the Stratix® V overview page.
For details on the memory block counts for earlier Stratix® FPGA families, see the relevant handbook chapters.

Table 2 summarizes the features for each of the two internal memory types implemented in Stratix V FPGAs.

Table 2. Internal Memory Features in Stratix® V FPGAs





600 MHz

600 MHz

Simple Dual-Port

True Dual-Port



Packed Mode



Low-Power Mode

Shift Register



Mixed Clock

Byte Enable

Address Clock Enable