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?
They are mixers and summing amplifiers.
(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)