用有源器件设计二阶电流型滤波器

Design of second order current-mode active filter

分析了由零极子对和RC元件组成的基本电路模块,其基本电路的传递函数为二阶。可以用不同的有源器件取代基本电路中的零极子对,得到电流传输器型(CCⅡ型)和通用运算放大器型(OPA型)电路。每种电路都发挥了有源器件本身的特长,即CCⅡ型适用于高频电路,OPA型适用于低频电路。这2种电路分别只用了1个有源器件,不用改变电路结构,也不必调整RC的比值,同时可在3条支路中实现带通、高通和低通滤波功能。

The transformation function of a circuit composed of nullatornorator and RC component is of the second order. Thus, replacing the nullatornorator by active elements, circuits of currentconvey type (CCⅡ) as well as generalpurpose operational amplifier type(OPA) are obtained. Each of these circuits is capable of giving play to its distinctive feature: CCⅡ accommodating to high frequency and OPA, to lowfrequency. These two kinds of filter circuit can be implemented, respectively, by using an active element, without changing circuit configuration and not in need of adjusting RC ratios, functions of lowpass, highpass, and bandpass can be realized simultaneously in three different branches.