Electrical

Passive RC Low-Pass Filter Circuit

Electrical Diagrams · made in Skemio

Ladder schematic of an AC circuit with a 10V AC source across a series 1 k-ohm resistor and 159 nF capacitor, establishing a 1 kHz cutoff.
Ladder schematic of an AC circuit with a 10V AC source across a series 1 k-ohm resistor and 159 nF capacitor, establishing a 1 kHz cutoff.
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What it shows

  • Capacitive reactance Xc = 1 / (2πfC) drops inversely with signal frequency.
  • Cutoff frequency fc = 1 / (2πRC) marks the -3 dB attenuation corner point.
  • Signals beyond cutoff roll off at a steady -20 dB per decade slope.

The takeaway

An RC low-pass filter passes DC while smoothly shunting high-frequency signal noise to ground.

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