Multiple feedback order filter circuit and design method based on switch modulation

Abstract

The invention provides a multi-feedback type order ratio filtering circuit based on switching modulation and a manufacturing method. The multi-feedback type order ratio filtering circuit comprises a control signal input end, a first resistance switching serial module, a second resistance switching serial module, a third resistance switching serial module, a capacitor C1, a capacitor C2 and an operational amplifier. The circuit provided by the invention has an order ratio filtering function; circuit design can be completed only in need of the ordinary operational amplifier and resistance-capacitance; the input signal range of the circuit provided by the invention is only determined by working voltage of the operational amplifier; if the working voltage of the operational amplifier is + / - 15V, the input signal range is close to + / - 15V; and the circuit disclosed by the invention is simple in structure and convenient to design.

Description

technical field [0001] The invention relates to electronic technology, in particular to a multi-feedback order filter circuit based on switch modulation. Background technique [0002] In the test of the vibration and noise signals of the rotary machinery, for the case of uniform rotation, sampling at equal time intervals is generally adopted and conventional spectrum analysis is performed. However, in the process of speed change, sampling at equal time intervals will make the frequency components on the spectrogram blurred. To this end, the signal must be analyzed using a sampling sequence of equal rotation angles, the so-called order analysis. [0003] Assuming that the number of samples per revolution of the rotary machine is E S , according to the order sampling theorem, in order to avoid aliasing, E must be filtered out of the signal before order sampling S / 2 or higher order components. Obviously, if the general low-pass filter method with fixed cut-off frequency is...

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Problems solved by technology

Obviously, if the general low-pass filter method with fixed cut-off frequency is adopted, when the variation range of the rotational speed is large, the following problems will be brought about: at a certain cut-off frequency, at low speed, at E S There may be aliasing around / 2; at high speeds, the signal of interest may be filtered out sufficiently

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