Fractional-N divider using a delta-sigma modulator

摘要

A delta-sigma modulator having a dead-zone quantizer and an error shaping digital filter clocked by a signal which is periodic at the frequency of the reference. A dead-zone quantizer provides quantization of a high resolution digital word to a low resolution digital word with three or a higher odd number of possible output levels and with an output of zero for an input near the center of the normal input range. The delta-sigma modulator is used in a fractional-N divider. The fractional-N divider is used in a fractional-N frequency synthesizer.