改进的双二阶节有源滤波器

Modified Biquadratic Active Filter Sections

改进的双二阶节有源滤波器吴 陵（东南大学电子工程系，南京２１００１８）带虚零点的双二阶节是采用综合法设计的高阶滤波器（如椭圆函数型、一般参数型）的主要的基本组成单元．在低频（１００ｋＨｚ以下），采用有源滤波器是较理想的，其中“Ｇ．Ｉ．Ｃ”ＢＭＡ双二节?..

The biquadratic active filter sections using generallzed-immittance converters(“G. I. C”BMA )are analysed and improved. A value K is defined as the nor mallzed characteristic of degree inwhich imaginary zeros of biquadratic section transfer function close to poles. It is solved in themedified filters that when using frequency bands are relatively high,errors of transfer functions of“G. I.C”BMA filters are large because of nonideal operational amplifiers,especially,the imaginaryzeros of transfer function almost vanish in high Q and high K biquadratic active section. It is solvedalso that“G. I.C”BMA filters frequently fall into high or low frequency self-excitation.A newdesign method and a speclal adjustment method to approach ideal transfer function are describe.