What are the major spectral impurity components of direct digital synthesizers?
Broadband noise
Digital conversion noise
Spurious signals at discrete frequencies✓الإجابة الصحيحة
Harmonics of the local oscillator
الشرح
Phase truncation, limited lookup-table depth, and digital-to-analog converter nonlinearity all put energy at specific frequencies related to the clock and output frequencies. The result is discrete spurious signals rather than a raised broadband noise floor.