DSP Builder for Intel® FPGAs (Advanced Blockset): Handbook

ID 683337
Date 5/27/2022

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Document Table of Contents Creating Floating-Point Accumulators for Designs that Use Iteration

In DSP Builder, you can create fixed-point accumulators with one or more channels, but you cannot create floating-point equivalents.


  1. If your design requires a single channel accumulator, use the Acc block.
  2. Use multiple channels where the number of channels is at least as large as the latency of the floating-point adder. The lower limit on the number of channels depends on fMAX, device family, and speed grade:
    1. DSP Builder redistributes sample delays in your multiple channel accumulator. You cannot rely on DSP Builder preserving the reset state of zero. Use a 2:1 Mux block in your accumulator to make the initial state explicit.
    2. Use the custom SameDT block to avoid any data type propagation problems in feedback cycles.