Phase noise shaping using sigma delta modulation in a timing recovery unit

A method and apparatus for converting a high precision digital word into a high precision analog signal is disclosed. A sigma delta modulator applies a digital input signal to a dither signal to generate a combined signal for sampling. A digital-to-analog converter quantizes the combined signal. An...

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Bibliographische Detailangaben
Hauptverfasser: LIU TONG, GORECKI JAMES L
Format: Patent
Sprache:eng
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Zusammenfassung:A method and apparatus for converting a high precision digital word into a high precision analog signal is disclosed. A sigma delta modulator applies a digital input signal to a dither signal to generate a combined signal for sampling. A digital-to-analog converter quantizes the combined signal. An analog filter provides a cutoff at a bandwidth of interest to remove out of band quantization noise and signals. An I transfer function and a Q transfer function can be coupled between the sigma delta modulator and the digital-to-analog converter for mapping of the combined signal. The apparatus can also include a phase interpolator for receiving the output signal and outputting a clock recovery phase.