Current-Mode Active Filters Based On The Third-generation Current Conveyor

Current-mode filters have been paid more attention for their high speed,lower p ower consumption,wider dynamic range and compatibility with VLSI technology.Current conveyor is a standard component of current-mode circuits.At presen t,the study of current-mode continuous-time filter based on current conveyor inside and outside of the country is basically the second generation current conveyor techni que and the improved technique of CCⅡ.but,the study on CCⅢand its improved cir cuit,the design of current-mode filter based on CCⅢjust begin.because of the CCⅡonly has a singe output,so,there are two shortages about the design of filter.(1) curre nt direct and feedback can not be done at one time.if carry out current feedback will breach the high output resistance.(2)the circuit design is too complex,it need some ne gative and active parts of apparatus.The third generation current conveyor compare to CCⅡhas some characters,such as low plus error,good linear character,wide frequent cy response and high output impedance.So the current-mode continuous-time filter b ased on CCⅢbecomes the new research direction in the world.Just as the reason,thi s paper studies the design of the third generation current conveyor and the fully inte grated current-mode continuous-time filter.It is based on the design idea of some existing CCⅡcircuits,falling to designing the third generation current conveyor filter.Becaused of the basic current mirror used in structure of the conventional CCⅢ,its impendence is too low,so its DC and AC performances are low.In this pape r,we improve the current mirror of the basic structure.Apply the Self-biased current so urce and RGC stage to compose a current mirror,which provided high output impen dence.Provided current conveyor perfomance.Beside,This article describes a new me thod of changing the variable of state active RC filter to current-mode filter base on th e third-generation current conveyor.The filter can realize second order low-pass,hig h-pass,band-pass filtering functions.The proposed circuits have not only simple struc ture,low passive and source sensitivity,but also source parameter has nothing of pole frequency W_o.The results of HSPICE simulation demonstrate the feasibility of the pr oposed circuits.Base on TSMC(0.35UM BICMOS 3P3M)and assure tools,have finish ed the layout of CCⅢand low-pass,high-pass,band-pass filter,and passed the check of DRC and LVS.