基于CCⅡ的双二次滤波器的设计方法——替换法

A Design Method for CCⅡ Based Biquadratic Filters The Replacement Method

用ＣＣⅡ构成的基本块替代由运放构成的相应基本电路，就能将经典的有源ＲＣ二阶滤波器转换成基于ＣＣⅡ的相应滤波电路．还给出了由ＣＣⅡ实现的单端和差动电压放大器以及由ＣＣⅡ实现的构成状态变量波滤器的基本块——相加积分器、加权加法器等．替换法既能把ＳＡＢ电路转换成ＣＣⅡ基础上的相应滤波器，也能把状态变量有源ＲＣ滤波器转换成ＣＣⅡ基础上的滤波器．由替换法实现的ＣＣⅡ基础上的滤波器，不仅保留了原型电路的滤波功能和灵敏度特性。

A new CCⅡ based biquadratic circuit design method known as the replacement method is presented in the paper. By using the method, an active RC biquadratic filter can be converted to CCⅡ based circuit by replacing op amp circuits with CCⅡ circuit blocks. Signal input and differential voltage amplifiers and kinds of state variable filter blocks constructed by CCⅡs such as summing integrator and CCⅡ weighted summer are also given in the paper. Not only every kind of SAB circuits but state variable active RC biquad(or high order) filters can also be converted to CCⅡ based filters. The new filters have the same characters in sensitivity as the original ones but have a better high-frequency characters than the original.