DDS Stream - 2022.1 English

Vitis Model Composer User Guide (UG1483)

Document ID
Release Date
2022.1 English


AI Engine/DSP/Stream IO


This block implements the stream-based Direct Digital Synthesizer (DDS) targeted for AI Engines.


Output Data Type:
  • Describes the type of individual data samples output of the DDS function. It should be cint16 or cfloat.
Output Frame Size (Number of Samples):
  • Specifies the number of samples in the output frame. The value must be in the range 8 to 1024 and the default value is 32.
Number of Parallel Outputs (SSR):
  • This parameter specifies the number of output ports and must be of the form 2^N, where N is a non-negative integer.
Phase Increment:
  • Specifies the phase increment between samples. The value must be in the range 0 to 2^31 and the default value is 0. Input value 2^31 corresponds to Pi (i.e., 180). Phase increment is calculated using the formula (Fo*(2^N)) / Fs where:
    • Fo = Output frequency.
    • N = 32, which represents the accumulator width, and it is fixed.
    • Fs = Sampling frequency.
Initial Phase Offset:
  • Specifies the initial phase offset. The default value is 0.
Sample Time:
  • Specifies the sample time for the block output port. The default value is -1.
Target Output Throughput (MSPS):
  • Specifies the output sampling rate of the DDS function in Mega Samples per Second (MSPS). The value must be in the range 1 to 1000 and the default value is 200.