DIRECT DIGITAL SYNTHESIZER, REFERENCE FREQUENCY GENERATING DEVICE, AND SINE WAVE OUTPUTTING METHOD

摘要

A DDS achieved in size and cost reductions by removing a ROM for storing a table and the like and suppressing an operation amount is provided. A DDS includes an NCO, a DAC, and a BPF. The NCO outputs a sawtooth wave. The DAC converts either one of the sawtooth wave outputted from the NCO and a triangle wave signal converted by a waveform converting circuit based on the sawtooth wave, from a digital signal into an analog signal. The BPF receives the signal converted into the analog signal by the DAC and extracts a sine wave at a predetermined frequency from the inputted signal, by allowing a signal at a frequency within a fixed range to pass therethrough.

主权项

1. A direct digital synthesizer, comprising:
a numerically controlled oscillator configured to output a sawtooth wave; a DAC configured to convert either one of the sawtooth wave outputted from the numerically controlled oscillator and a signal obtained based on the sawtooth wave, from a digital signal into an analog signal; and a band-pass filter configured to receive the signal converted into the analog signal by the DAC and extract a sine wave at a predetermined frequency from the inputted signal, by allowing a signal at a frequency within a fixed range to pass therethrough.