说明：  介绍了滤波器的基本原理 本节所述内容属于模拟滤波范围。主要介绍模拟滤波器原理、种类、数学模型、主要参数、ＲＣ滤波器设计。尽管数字滤波技术已得到广泛应用，但模拟滤波在自动检测、自动控制以及电子测量仪器中仍被广泛应用。
(Introduce the basic principles of the filter elements described in this section belong to the scope of analog filtering. Introduce the main principles of analog filters, the type of mathematical model, the main parameters, RC filter design. Although the digital filter technology has been widely used, but the analog filter in automatic detection, automatic control and electronic measuring instruments in the still widely used.)