Error feedback loops linearize direct digital synthesizers

The fidelity of a signal formed by the sequence of recalling stored digital samples from a look-up table and then converting these sample amplitudes to a waveform in a digital-to-analog converter (DAC) is affected by the time and amplitude quantization of the process. The size of the look-up table, hence the number of bits in the addressing scheme, affects the signal's time resolution and results in time-base jitter while the number of bits in the DAC affects amplitude quantization. These errors can be reduced by using noise feedback to spectrally shape the quantization noise formed by the table's address generator and of the quantization noise of the sample values presented to the DAC.<
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