1. Field of the Invention
The present invention relates generally to synthesizers and, more particularly, to direct digital synthesizers.
2. Description of the Related Art
A direct digital synthesizer generates analog signals that correspond to input tuning words and a synthesizer clock which also determines the synthesizer's Nyquist range. Although direct digital synthesizers provide a number of advantageous features (e.g., phase-continuous switching, high frequency resolution and fast switching time), they typically generate spurious signals which unduly limit their spurious free dynamic range. This limitation continues to be the most serious deficiency of direct digital synthesizers.