Filter Introduction I

Classification of filters

Filter is a network consisting of the resistors, inductors and capacitors of the concentrated parameters or distributed parameters. It allows some frequencies to pass through while suppressing other frequencies.

It is divided into LPF, HPF and BHF from the cutoff frequency.

It is divided into low frequency filter, intermediate frequency filter and high frequency filter from operating frequency.      

It is divided into active and passive filters from used devices.

Passive filter is divided into RC filter and LC filter. RC filter is divided into low-pass RC, high-pass RC , band-pass RC and band-stop RC. So the same as LC filter.

Active filter is divided into active high pass filter, low pass filter, band pass filter and band stop filter.

Parameters of filter

1.  Insertion Loss(dB): The greater the dB value, the stronger the ability to suppress noise interference.

2. Cutoff frequency: If the insertion loss of the filter is greater than 3 dB, the frequency point is called the cutoff frequency. When it exceeds the cutoff frequency, the filter enters the stopband, and the interference signal in the stopband will be greatly attenuated.

3. Rated Voltage: The voltage that the filter can withstand for a long time when it works normally. It is divided into AC and DC.

4. Rated Current: The current that the filter can withstand for a long time when it works normally.

5. Climate Category

6. I Leakage

7. Test Voltage: The maximum voltage that the filter can withstand