Research Of Adaptive Filter

Adaptive detection has broad applications. Based on the full study at various types ofadaptive filtering method, pointing at the current analog adaptive filter’s low signalprocessing speed and the not achieving filter frequency automatic tracking and othershortcomings, the study designs an new kind of analog adaptive filter which pass-band canadapted with the frequency range of the input signal of dynamic regulation, applicable to awide range of signal frequency, high-speed and intelligent signal processing occasions analogadaptive filter.The key research questions are as follows: to study the design theory of all the kinds ofhigh-performance filter which based on current-mode technology, to make full use ofcurrent-mode circuit wide frequency range, high signal processing speed and other advantages;to research wideband frequency-to-voltage converter (F/V) circuitwith the design of methods,to solve the problem of existing F/V chips only can allow low frequency signal to beconverted, to indirectly achieve signal’s adaptive filtering; to use multiplier in a variety offilter circuit design, to reduce the degree of complexity of the circuitry of the programmablefilter.The major of the article is summarized as follow：(1) After reading a lot of references, the essay introduces adaptive filter status,applications, development prospects, and summarizes and compares existing digital adaptivefilter algorithm and analog adaptive filter design methods, proposing a use ofhigh-performance the F/V chip LM331, combining analog multiplier and current feedback opamp to achieve the cut-off frequency quickly and automatically adapt to the design of analogfilters to be processing the signal frequency changes.(2) The article details the working principle and the nature of each generation currentconveyor, and current feedback op amp topology and closed-loop characteristics; and thedesign uses current feedback op amp achieved the basic simulation unit; describes the activefilter which based on current feedback op amp basic design method.(3) The design achieves broadband F/V circuit by using frequency divider circuit,amplifier circuit, main circuit and the F/V chip, and measures the circuit designexperimentally which can achieve30M signal processing.(4) The design also does the signal conditioning circuit, including amplification, limitingand shaping. The design of the amplifier circuit uses current feedback op amp and resistornetworks, the use of high-frequency diode in parallel bi-directional limiter circuit; useshigh-speed comparator MAX903and resistor networks to make up overvoltage comparator toshape signal. We also do some measurements on the circuit design of the experimentally (5) By using analog multiplier and current feedback operational amplifier, we achievedvoltage-controlled filter circuit. And a variety of voltage-controlled filter circuit designs areanalyzed theoretically and pass the ORCAD simulation software’s examination, part of thecircuits are experimental measured.The analog adaptive filter designed in this paper can achieve the function that the passband of it can be adjusted dynamically with the input signal’s frequency range and canachieve the automatic tracking function of the filter frequency. The frequency characteristicscan be used for analysis, harmonic analysis, frequency detection, radar signal detection hasimportant theoretical significance and application prospects.