说明：  以把直接数字频率合成（DDS）看成这样一种技术，它能用数字值形式的信号控制正弦波的频率。最简单的DDS电路包括一个二进制计数器，一个以等间隔正弦波值进行全波编程的ROM，以及一个数模转换器，用于将存储的正弦波值转换为电压。计数器的时钟频率决定了正弦波的频率，但这种结构并不灵活。
(To the Direct Digital Synthesis (DDS) as such a technology, it can use the digital value of the form of the frequency of sine wave signal control. The simplest DDS circuit includes a binary counter, such as between a full-wave sine wave value programmed ROM, and a Digital to Analog, used to store the value of the sine wave into a voltage. Counter clock frequency determines the frequency of sine wave, but the structure is not flexible.)