Passive filters

What It Does

Filters are used to remove unwanted frequencies from a signal. They can be used to remove noise, remove DC offsets or for waveshaping. Passive filters do not use active components like op-amps and transistors, but only resitors and capacitors.

Formula (fc = cutoff frequency in hertz)

fc = 1 / (2 * π * R * C)

Low-pass RC filter

A low-pass RC filter is a passive filter circuit that allows low-frequency signals to pass through while attenuating high-frequency signals. It is one of the simplest and most common types of filters. The basic circuit for a low-pass RC filter consists of a resistor and a capacitor connected in series.

• Notice the name of the circuit: R (resistor) C (capacitor).

High-pass RC filter

A low-pass RC filter is a passive filter circuit that allows high-frequency signals to pass through while attenuating low-frequency signals.