Date Added: Feb 2013
Frequency synthesizers are very critical blocks for embedded systems in communications and instrumentation applications. Direct digital frequency synthesis is widely used technique, due to its high frequency resolution and fast switching between frequencies over a large bandwidth of interest. The DDFS in modulator mode can be used for producing ASK, FSK and PSK signals. In pattern generation mode the DDFS can be used to generate sine, square, triangular and arbitrary waveforms. The term "Frequency synthesis" applies to a technique that accepts some reference input and then generates one or more signals of predefined type as according to a control word or method. The stability, accuracy, and spectral purity are the performance measures of frequency synthesizer.