利于集成且对杂散电容抑制性极佳的开关电容型滤波器

采用单位缓冲器设计对杂散电容不灵敏的开关电容(SC)频率相关负电阻(FDNR)元件,利用该元件对椭园函数式LC低通滤波器进行SC模拟。为了获得电容最佳值,提出了一种简单的最优化方法。并采用寄生电阻预畸变与SC负电阻相结合的办法,设计的SC滤波器对杂散电容不灵敏,且电路简单。本文采用分立元件制作了一个五阶椭园低通SC-FDNR滤波器,实验结果表明该方法实用可行,效果明显。

Switched-capacitor Filters of Advantageous Integrated and Best Repressing Parasitic Capacitance

An unit buffer is adopted to design frequency dependence negative resistance（FDNR） element of switched-capacitor （SC） which is insensitive to parasitic capacitance. The element is used to simulate LC low pass filter of ellipse function by SC. This paper presents a simple optimization method to get the best value of the capacitance. The SC filter is insensitive to parasitic capacitance implemented by a simple circuit in the way of combining predistortion of parasitic resistance and SC negative resistance. Discrete components are applied to construct a five step ellipse low pass SC-FDNR filter. The experiment results indicate that the method is practical and efficient highly.