The circuit of Figure 1 produces an accurate variable-frequency sine wave for use as a general-purpose reference signal. It includes an 8th-order elliptic, switched-capacitor lowpass filter (IC3) that is clocked with a 100kHz square wave generated by microcontroller IC2. (Any other convenient squarewave source is also acceptable.) The microcontroller is clocked by a 10MHz oscillator module. A voltage supervisor (IC1) ensures correct operation in the event of a power failure. IC3 sets the filter's cutoff frequency at 1/100 the clock frequency.

翻译：

该电路 如图1 产生一个通用的参考信号准确，可变频率的正弦波使用。 它包括一个8阶椭圆形，开关电容低通滤波器（IC3的），是IC2的时钟与微控制器为100kHz方波产生的。 （任何其他方便的方波 来源 也是可以接受的。）微控制器是模块时钟由10MHz的振荡器。 一个 电压 监控 （IC1的）确保正确操作停电事件中的一个。 IC3的套/ 100的时钟频率滤波器的截止频率为1，同时保持它们之间的比例为100:1数字可调的正弦信号源。