Electronic filter

Electronic filters are electronic circuits which perform signal processing functions, 

specifically to remove unwanted frequency components from the signal, to enhance wanted ones, or both

. Electronic filters can be:

• passive or active
• analog or digital
• high-pass, low-pass, bandpass, band-reject (band reject; notch), or all-pass.
• discrete-time (sampled) or continuous-time
• linear or non-linear
• infinite impulse response (IIR type) or finite impulse response (FIR type)

The most common types of electronic filters are linear filters, regardless of other aspects of their design.

 See the article on linear filters for details on their design and analysis.