Spurious Free Dynamic Range is a parameter used to characterize signal generators. It measures the ratio between the amplitude of the fundamental frequency of the signal generator to the amplitude of the strongest spur. The dds_mixer_lut generates slightly different designs based on the SFDR requested by the user. The different implementations offer tradeoffs between the SFDR of the waveform generated and the throughput. Three different implementations are available, for SFDR less than 60dB, less than 120dB and for less than 180dB. Note that with the cint16 data type the maximum SFDR is 120dB.