Research Of High-order Filter Based On CDTA

With the rapid development of information technology,analog filter which is used to separate the useful and useless signal is an important part in the information industry,its performance directly affects the quality of the information system.AS the advantage of current-mode circuits,the current-mode filter is a hot topic in the field of microelectronics and integrated circuit research both in domestic and overseas.The filter based on current difference transconductance amplifier(CDTA)with high speed,low power consumption,large dynamic range,good linearity and the characteristics of simple structure,has the maximum potential in filter design.This paper mainly focuses on the study of high-order filter based on CDTA.Firstly it introduces the research status of filter,CDTA.Then summaries the development of the filter based on CDTA.And it introduces the basic theory of current-mode circuit,CDTA,filter.Refer to the research of current mode circuit,CDTA,filters,the paper came up with high-order low-pass filter which are based on CDTA and the recursive method,and also proposed reconfigurable nth-order filter based on CDTA for multi-mode filtering applications.The main innovations and works about this dissertation are as follows:(1)A high-order low-pass filter based on CDTA using recursive method is presented.The method is that the theoretical calculation for typical high-order low-pass filter transfer function is made using recursive method,then obtain the corresponding signal flow graph,as with the principle of CDTA,finally achieve the required high order low-pass filter.The circuit consists of n CDTA and n capacitance,what's more it has no resistance.And compared with others,the proposed circuit possesses the simple constructions,it can realized any even order low-pass filter by altering the size of n.(2)A reconfigurable nth-order filter based on CDTA for multi-mode filtering applications is presented.The proposed multifunctional filter consists of n DPCDTA and n capacitances,it can realized three filter function(Low Pass,Band Pass,High Pass)by altering the reconfigurable switch.The advantage of proposed filter is that the order can be changed and it's cut-off frequency can be tuning.In order to verify the correctness of the designed circuits,the two presented circuits are respectively simulated by Cadence and PSpice,and the simulation results match the results of theoretical analysis.