The Design Of Integrated Active Filter With Transmission Zeros

Active filter is widely used in various circuits and systems, including communications, signal processing, radar, measurement instruments and power system, which is an important circuit module for signal processing, and is one of the research hot point for system on chip. Thus the study of the integrated active filter has great practical value.Firstly the development and the design of active filter are presented, and the active components used in the active filter are introduced in detail, which are the theoretical basis for the following research. The 5th-order elliptic filters with two transmission zeros are used as an examples in the paper because of the elliptic low pass filter is superior to other types of filters in magnitude response, signal flow graph of elliptical low pass and high pass filter are derived based on the resistive doubly terminated passive filter whose theory is very developed and perfect, and the corresponding single-ended active RC filter circuit and the full-differential active RC filter are also realized.In the design process of integrated active filter, two cases that the circuit noise is considered or not are both analyzed, and the circuits of which are simulated for the purpose of comparison.Lastly, the simulation results show that the characteristic curves of the full-integrated active filter which is designed by signal flow graph is identical to that of passive LC filter, which means the method meets the required specifications and is effective and practical.A large number of examples are provided in the paper, to verify the feasibility and the superiority of the design method.