直接数字合成(DDS, direct digital synthesizer)是一种把一系列数字信号通过D/A转换器转换成模拟信号的数字合成技术。DDS函数信号设计由相位累加器、波形存储器、D/A转换器和低通滤波器构成。FPGA完成相位累加和波形存储器设计, 输出数字序列, 经过D/A转换器和低通滤波后, 产生模拟信号。使用示波器显示验证, 将波形频率上限为5 KHz的单片机电路提升为20 KHz, 并提高信号精度。本方案进行了大量实验验证, 可以广泛应用于可编程片上系统。

Direct digital synthesis (DDS) is a digital synthesis technology that converts a series of digital signals to analog signals via digital to analog (D/A) converters. DDS function signal designing system consists of a phase accumulator, a waveform memory, a D/A converter and a low-pass filter. The design of phase accumulation and waveform memory is implemented by field-programmable gate array (FPGA), digital sequence is output, and the analog signals are generated via D /A converters and low-pass filtering. Using the oscilloscope to verify the waveform, the 5 KHz maximum waveform frequency of the single-chip circuit is enhanced to 20 KHz and the signal accuracy is improved. The scheme is verified by experiments and can be widely used in programmable systems.