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Filter Principle
Sep 06, 2018

The classification of filters has been described in detail before. In our daily use, the most common classification method is to divide it into four types: low pass, high pass, band pass and band stop. Then we will tell the principles of these four types of filters.


A low-pass filter usually refers to a circuit in an on-board amplifier that allows only low frequencies to pass, rather than medium and high frequencies, and drives the woofer unit by enhancing the woofer. Usually, class AB amplification design is adopted, and the power loss is relatively large. Different low pass filters reduce the same frequency signal to different degrees.


A high-pass filter, in contrast to a low-pass filter, means to block the signal of the low frequency band, and make the signal higher than a certain frequency band pass. The same as a low-pass filter, different high-pass filters weaken the signal of the same frequency band to different degrees.


Band-pass filter should have a completely flat passband, outside the pass band frequency signal attenuation out completely, but it is an ideal, in real life bandpass filter, and can't duly to all don't need to signal filtering, the existence of a small frequency conversion, usually called this the filter roll-offs phenomenon.


The band stop filter is opposite to the band pass filter, which means to block the signal of a certain frequency band and make the signal of higher or lower frequency band pass.