In summary, the DACs used in ADI’s high speed, high performance DDSs are usually of the balanced current-output variety. An ideal DDS (i.e., no phase truncation) with an ideal DAC only exhibits quantization spurs in its output spectrum, which is identical to the map spectrum. A real DAC, however adds both random noise and harmonic distortion to the output spectrum. The random noise increases the noise floor, while harmonic distortion adds harmonic spurs to the spectrum. For most DACs, the limiting factor of spurious-free dynamic range (SFDR) is harmonic distortion. That is, harmonic spurious components are usually significantly greater than either the random noise or the quantization spurs.