Adjustable-bandwidth And Fast-response To Time-varying Low-power-filter

Filtering technology is an indispensable part of signal processing.It is a key issue to design a filter with good performance.In practical application and production activities,a lot of useful information are carrying by the weak low-frequency signals,so the significance of low-pass filter is able to extract useful low-frequency signal from the noise signals,so low-pass filter design and development is essential.For a long time,people are committed to design the circuit which has the advantages of easy integration,low power consumption,high precision,low drift and so on,and widely used in measurement,communication,instrument and other fields.However,in many practical signal processing and measurement applications,when the system input signal has the mutation,the output signal of the filter is difficult to follow the change of the input signal because of input signal's edge signal contains many frequency components.In the filter design,we hope the filter have high filtering quality and fast respond speed.However,for the traditional constant parameter filters,because of its constant bandwidth,it can hardly satisfy both of requirements at the same time.In many applications,the respond speed is as important as the accuracy.Now some literatures have research on the theory and implementation of fast filtering technology.Fast filtering technology has a wide range of application requirements,at the same time for innovation has been quite mature filter theory and technology is important.The purpose of this paper is to design a fast response time-varying analog low-pass filter with adjustable bandwidth to ensure the filtering quality and respond speed.It is devoted to the practical application of the theory and technology.The main work and in this article are:(1)In analog domain,we focus on the analysis of first-order and second-order time-varying low-pass-filter with step type bandwidth and continuous bandwidth,using Matlab get the notional result.(2)Design a method for detecting two kinds of input signal mutations for continuous unit steps and mixed with noise of ladder.(3)Design a JFET-based circuit for realizing a precision and linear floating voltage-controlled resistance.(4)On the basis of the constant parameter low-pass filter,time-varying low-pass filter with adjustable bandwidth step and continuously is designed.For the case where the input signal of the bandwidth adjustable time-varying low-pass filter is a continuous unit step signal and a mix with noise of ladder signal,the effect of effective noise reduction and fast response has been verified by simulation.The simulation results show that the proposed method is effective and has a certain engineering application value.