Method and apparatus for synthesizing signals with phase continuous and phase coherent transitions

摘要

A direct digital synthesizer (DDS) includes a phase increment calculator that determines a phase increment for a selected frequency; a phase accumulator that accumulates the phase increment over time and provides an accumulated phase value; a converter that converts the accumulated phase value to an analog signal at the selected frequency; and a phase preset calculator that determines a phase preset value for the selected frequency. The phase accumulator resets the accumulated phase value to the phase preset value at a transition to the selected frequency in a phase coherent mode.

主权项

1. A direct digital synthesizer (DDS) comprising:
a phase increment calculator configured to determine a phase increment for a selected frequency; a phase accumulator configured to accumulate the phase increment over time and provide an accumulated phase value; a converter configured to convert the accumulated phase value to an analog signal having the selected frequency; and a phase preset calculator configured to determine a phase preset value for the selected frequency and output the phase preset value to the phase accumulator, the phase accumulator further configured to output the accumulated phase value in a phase continuous mode and preset the accumulated phase value to the phase preset value at a transition to the selected frequency in a phase coherent mode.