The Research Of Current Mode Filters Based On Current Controlled Conveyor

A continuous time filter is an important subject in microelectronic, circuit and system. It is applied widely in communication, electronic measurement, instrument & appearance and intelligent control. Current mode filters have been paid more attention for their high speed, lower power consumption, wider dynamic range and compatibility with VLSI technology. Current mode filters based on current conveyor (CC) , particularly the second generation current conveyor (CCII), should be most potential with larger signal bandwidth, simpler circuit structure and better linearity. CCII has, however, the disadvantage to present a non-negligible output parasitic resistance on port X. The parasitic resistance leads to conversion errors when a load resistance is connected at port X, or to incorrect transfer function when this load is a capacitor. Moreover, filters based on CCII suffer from the lack of electronic adjustability. In this paper, we study the realizations and design methods of the second order and high order current mode filters based on multiply outputs current controlled conveyor (MOCCCII). The main achievements consist of as following aspects: 1. The realization of the MOCCCII and its hardware circuit. The MOCCCII is present with replicating across current mirror on CCCII and it's hardware circuit is completed by using BJT such as S9014 and S9015. The experiment results are in good agreement with the port property of MOCCCII. 2. The design of current mode biquard filters based on MOCCCII. In this paper, five current mode filters, including current mode filter with three input-single output, current mode filter with biquard input-single output, current mode filter multiply input-multiply output and current mode filter with single-input multiply output are present. All of these filters have advantage to be simple circuit structure, totally function and they are of electronic adjustability. 3. A systematic design theory and method for high order current mode filter is proposed with MOCCCII. The paper presents a new general synthesis method for the nth order current mode filter based on MOCCCII. The method is based on the analytical solution of a single, nth-order generic filter transfer function and the generation of n number of realizable transfer functions using lossless integrators. The filter structure presented simply contains n active elements and n grounded capacitors. Various kinds of filters can be realized just by changing the amount and mode of joining external current signals without changing internal circuit structure and the amount of elements. So the circuit is convenient to integrated. 4. A novel nth current mode filter is present The filter structure presented simply contains n+1 active elements and n grounded capacitors. Various kinds of filters such as high-pass, low-pass, band-pass, notch and all-pass can be realized. 5. The design of fully differential current mode filter based on MOCCCII. The fully differential continuous time current-mode integrator based on MOCCCII is presented. Employing the integrator the basic filters such as low pass and band-pass are made up. The performances of the integrator and filters are analyzed. Pspice simulation for actual circuit is conducted, and the result shows that the presented circuit is valid and effective.