All courses › Electronics › RC Low-Pass Filter

RC Low-Pass Filter

An RC low-pass filter passes low frequencies and attenuates high ones. At the corner frequency fcf_c the amplitude has dropped to 1/21/\sqrt2 of its low-frequency value, i.e. −3-3 dB, and above fcf_c it keeps falling at 20 dB per decade.

fc=12πRCf_c=\dfrac{1}{2\pi RC}corner frequency of an RC low-pass

Symbols

RRresistanceΩ\Omega
CCcapacitanceF
fcf_ccorner frequencyHz

Example

R=10R=10 kΩ, C=100C=100 nF:

fc=1/(2π⋅104⋅10−7)≈159f_c=1/(2\pi\cdot10^4\cdot10^{-7})\approx159 Hz.

At fcf_c the gain is 1/2≈0.7071/\sqrt2\approx0.707, i.e. −3-3 dB, regardless of the values of R and C.
Practise filters and signals for free →

← Non-Inverting Amplifier · RC High-Pass Filter →

Part of Electronics: Filters and signals.