通用二阶滤波器的高频特性研究

为了获得高频率、高精度通用二阶滤波器，以运放的单极点模型为基础，分析了基本电路模块的开环频率特性及其一级近似，给出了TT滤波器、KHN滤波器的特征方程，在一级近似条件下求出了2种滤波器极点频率和品质因素的计算式．结果表明：在高频场合，2种滤波器均会出现“Q移位”和“ω0移位”现象，即TT滤波器只会出现Q增强和ω0减弱现象，而KHN滤波器不仅会出现Q增强和ω0减弱现象，而且也会出现Q减弱和甜。增强现象．最后以KHN滤波器为例，取Q=0．612，通过频率预失真技术，消除了“Q移位”和“ω0移位”现象，给出了foa=100kHz，Qa=0．612的KHN滤波器．计算机仿真表明理论分析正确无误．

Research on High Frequency Characteristics of Universal Second Order Filter on OP

In order to obtain universal second-order filter with high frequency and high accuracy, the frequency response of circuit modules using actual OP was analyzed based on the open-Sloop frequency response of actual OP. The characteristics equations of ＂IT and KHN filter on OP＇ s and the first order approximate equations of the Qa and to ω0a of the filter were given. The Q and too shifts in the filter were analyzed. The Q enhancement and too reducing effects were only found in TT filter. The effect of Q enhancement and too reducing and the effect of Q reducing and too enhancement were all found in KHN filter. Finally, for Q = 0.612, the shifts in the Q and ω0 of the filter can be eliminated by frequency pre-distortion. The KHN filter with foa = 100 kHz, Qa = 0.612 was given. The results of computer simulation show that the analysis method is valid and effective.