截止频率精确可调跨导电容滤波器实现Realization-电子与信息学报.PDFVIP

第28 卷第7 期 电 子 与 信 息 学 报 Vol.28No.7 2006 年7 月 Journal of Electronics Information Technology Jul.2006 截止频率精确可调跨导电容滤波器实现 江金光 王耀南 (湖南大学电气与信息工程学院 长沙 410082) 摘 要 提出了一种新的利用开关电容技术调节偏置电流值大小的电路，应用该电路可以精确调节跨导运放 Gm 值的大小。采用既具有电压共模负反馈(CMFB) 电路, 又同时具有工作在线性区的 MOS 管作源极反馈有源电阻, 实 现其良好线性度的跨导运放。设计了三阶椭圆函数低通滤波器，并实现其频率的精确可调。应用台积电(TSMC)2 层多晶硅，4 层金属(2P4M)，3.3V 电源电压，0.35 μm CMOS 工艺 Spice model 仿真得到的频响曲线与理想情况十 分接近。 关键词 电压共模负反馈, 频率可调, 跨导电容滤波器, 源极反馈有源电阻, 椭圆函数滤波器 中图分类号: TN713, TN432 文献标识码: A 文章编号：1009-5896(2006)07-1335-05 Realization of Gm-C Filter with Accurate Tunable Frequency Jiang Jin-guang Wang Yao-nan (College of Electrical and Info. Eng., Hunan University , Changsha 410082 , China) Abstract This paper presents a new circuit to tune Gm value of transconductor accurately which employs switched-capacitor technique to change the bias current of transconductor. A third order elliptical function lowpass filter with accurate tunable frequency is designed using transconductor that is not only with voltage common-mode negative feedback, but also with varying bias-triode transistors to improve the linearity of this circuit. Simulated results show that the practical frequency response of the filter is very near to that of idealized circumstance by applying TSMC 2-poly 4-metal 3.3V power supply 0.35 μm CMOS technology Spice model. Key words Voltage common-mode negative feedback, Tunable frequency, Gm-C filter, Source-degeneration feedback active resistor, Elliptical function filter