| 摘要 |
A direct digital synthesizing method, comprising the following steps: a phase accumulation module calculates based on a frequency synthesizing word and obtains a first phase (S101); searching a preset sine lookup table for an amplitude value according to the first phase (S102); searching a preset phase lookup table for a second phase according to the amplitude value (S103); if the second phase is less than the first phase, then adjusting the amplitude value for output (S105); otherwise, outputting the original amplitude value (S106); a digital-analog converter performs digital-analog conversion on the outputted amplitude value to obtain a sine wave output (S107). For an N-bit phase accumulation module and a D-bit digital-analog converter, the preset phase lookup table contains 2D-1-1 phase boundary value records corresponding to 0-2D-1-2 amplitudes, each phase boundary value being stored in N-2 bits. Also disclosed is a direct digital synthesizer (10) employing the above method. |
