Any Order Drift-free All-pole Active Low-pass Filter

The fundamental station of filter technology is widely recognized in modern information science. Because massive fundamental information in science and production activity loading on low frequency weak signal, low pass filter is widely applied to get the information and be designed to anti-jamming under the noise environment. Because passive RC filter can only implement the special transfer function with apices in negative x-axis and single radix, the active RC low pass filter is most suitable low frequency filters system. However, active filter with the implement method of direct synthesis, multi-section connection, multi-loop feedback and so on at present, because of direct connecting in the channel, can all import additive drifting which is produced by active devices. In domain of sea monitor, geological prospecting, construction, biomedicine, electrochemistry and so on, the system sensitivity in low frequency weak signal transmission, examination system and high accuracy instrument often reaches uV even nV. So at that time additive drifting has the same serious issue with noise.In order to restrain noise and do not cause new drifting questions at the same time, the request of amplifier used in filter system is very slashing and sometimes even cannot realize. Therefore, it is very important to develop a sort of non-drift active low pass filter system with high precision transmission and examination system for both the innovation filter theory and the anti-jamming design method.The goal of this article is in research of establishing the non-drifting active low pass filter system theory and the realization method, including the topology, the sensitivity analysis, the comparison with the tradition active low pass filter, the mathematical model and the algorithm design of the parameter optimizations to settle the contradiction between noise in tradition low pass filter and the additive drift.The main work and conclusion in this article are: (1)based on the circuit of non-drifting active low pass filter system, produces commonly used non-drifting low pass filter systems normalized optimal parameter in 7 steps and supplies for the needing of engineering; (2) the design problems of Non-drift all-pole Active Low-pass Filters based on non ideal operational amplifiers with limited gain and bandwidth are investigated through mathematical method and experimental test. The result indicate that ideal model of operation amplifier is accurate enough for the design of Non-drift all-pole Active Low-pass Filters. The design formulas are also given and have been proved correct by Pspice simulations; (3) based on the analysis method of the non-drifting active low pass filter system, the no relationship between the sensitivity and free variables and the definition of statistic sensitivity, through theory deduce, the paper puts forward an optimum method for statistic sensitivity of the non-drift all-pole active low-pass filters. It is proved by low rank system modal. And it can be deduced that when all the β_i is equal to one the system sensitivity is at the lowest. The decentralization rate of resistance and capacitance is much lower and the system design is much easier.The simulations in the article are all compiled and edited in Pspice and Matlab.