在许多超声和电子测试中，常常需要频率稳定、步进间隔小的信号源。例如超声共振法［１］就需要这样的信号源。但是，一般频率合成信号源价格昂贵，自制又有一定的技术难度。我们研制的ＤＦＳ－Ａ型频综信号源由于采取了数字混频等新技术，并尽量使用集成电路，具有结构简单、成本低等优点，可广泛用于学校、工厂和科研等单位。 In many ultrasonic and electronic tests, it is often necessary to have a frequency-stabilized, small-signal source. For example, ultrasonic resonance [1] requires such a signal source. However, the general frequency synthesis signal source expensive, self-made and have some technical difficulty. The DFS-A frequency synthesizer signal source we developed has been widely used in schools, factories and research institutes due to its advantages of simple structure and low cost because of adopting new technologies such as digital mixing and using integrated circuits as much as possible.