Research And Design Of CDTA-based Current-mode High-order Filter

With the development of the analog integrated circuit,the current-mode circuit has become the most important research in the field of integrated circuit.The current-mode time-continuous analog filter,which is the hot research topic in the current microelectronics technology,has been successfully applied in communications,signal and information processing,computer peripherals and other fields.The filter based on current differencing transconductance amplifier(CDTA),which has the advantages of wide frequency band,fast processing speed,low power consumption and low input and high output impedance,has the research significance in filter design.This paper mainly focuses on the study of higher-order filter based on CDTA.Firstly it introduces the research status of CDTA and filter based on CDTA.Then it expounds the basic theory of current-mode circuit,CDTA and filter,including the definition,characteristics and implementation methods.This paper proposes a new current-mode device based on CDTA:cascade current differencing unit.Meanwhile,a high-order current-mode filter based on cascade current differencing unit and a high-order multifunction filter based on CDTA are proposed in this paper.The main innovations and works about this dissertation are as follows:(1)A high-order multifunction filter based on CDTA is presented.The circuit consists of n CDTAs and n grounding capacitances,which can obtain wide bandwidth,low power consumption and simple structure.This paper provides a detailed theoretical analysis of the port characteristics.The simulation results of the third-order filter through PSPICE validate the correctness of the proposed circuit.(2)A novel current-mode active device is proposed based on CDTA,which is cascade current differencing unit(CCDU),and based on it a high-order current-mode filter is proposed.CCDU enriches the current-mode of device types,improves the flexibility of circuit design and largely simplifies the design of the high-order filter.The high-order current-mode filter is designed by only using a CCDU and n grounding capacitances,whose circuit structure is simple,meanwhile voltage and power consumption are low.The simulation results of the proposed third-order filter through PSPICE accord with theoretical analysis.In this paper,the presented two kinds of high-order current-mode filters can realize low-pass,high-pass and band-pass without changing the circuit.