对寄生电容不灵敏的开关电容有源FDNR滤波器的设计

采用单位缓冲器设计对寄生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滤波器对寄生电容不灵敏，且电路简单。在电子工作平台(EWB)上进行五阶椭园低通SC-FDNR滤波器仿真，测量数据最大相对误差为0．948％，仿真结果表明该方法实用可行，效果明显。

Design of Parasitic-capacitance Insensitive Switched-Capacitor Active FDNR Filters

An unit of buffer is adopted to design frequency dependence negative resistance (FDNR) element of switched-capacitor (SC) which is insensitive to parasitic capacitance. FDNR is used in SC to simulate LC low pass filter of ellipse function. A simple optimization method is used to select the most suitable value of the capacitance. In the process of SC design, an approach combining parasitic resistance pre-mutating and SC negative resistance is followed to achieve a simple filter circuit. Simulation of five-order ellipse low-pass SC-FDNR filter on electronic workbench (EWB) shows that the relative measurement error is below 0.948% as to verify the practical feasibility and high efficiency of the proposed filter.