I am taking a look at a DSP block for a the Xilinx ZCU111 FPGA and I am getting held up on a simple question. I come from physics so I am not too used to looking at block diagrams yet, but what do the highlighted components in the block indicate within the fine mixer?

Block Diagram for RFSoC FPGA DSP

  • 2
    \$\begingroup\$ Multiplication and addition. \$\endgroup\$
    – user16324
    Commented Apr 18, 2022 at 15:36
  • \$\begingroup\$ @user_1818839 Got it, so that would mean the multiplexed NCO signal is being multiplied by I_in and being added to NCO x Q_in \$\endgroup\$
    – mintl
    Commented Apr 18, 2022 at 15:47

1 Answer 1


They are mixers and summing amplifiers.

Basic architecture of a complex transmitter from Microwave Journal

(Image source: Microwave Journal - Complex RF Mixers, Zero IF Architecture, and Advanced Algorithms: The Black Magic in Next-Generation SDR Transceivers, Figure 3. Basic architecture of a complex transmitter)

  • \$\begingroup\$ Question is about a digital path, not RF. I'm curious if anyone in the digital world would call it a "summing amplifier"? \$\endgroup\$
    – johnnymopo
    Commented Apr 19, 2022 at 15:27

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