Low Pass Filter Calculator
Calculate the cutoff frequency (fc) of an RC low-pass filter with step-by-step logic.
Cutoff Frequency: 0 Hz
Calculation Steps:
What is a Low Pass Filter?
A Low Pass Filter (LPF) is an electronic circuit that allows signals with a frequency lower than a certain cutoff frequency to pass through, while attenuating (reducing the amplitude of) signals with frequencies higher than that cutoff frequency. The most common type is the passive RC low-pass filter, which consists of a single resistor and a capacitor.
The RC Low Pass Filter Formula
The relationship between the resistor (R), the capacitor (C), and the cutoff frequency (fc) is defined by the following formula:
Where:
- fc is the cutoff frequency in Hertz (Hz).
- π (Pi) is approximately 3.14159.
- R is the resistance in Ohms (Ω).
- C is the capacitance in Farads (F).
How to Use This Calculator
Using our calculator is straightforward. First, enter the value of your Resistor and select the appropriate unit (Ohms, kOhms, or MOhms). Next, enter your Capacitor value and select its unit (typically microfarads or nanofarads for audio and signal applications). Click "Calculate" to instantly see the cutoff frequency and a detailed breakdown of the mathematical steps involved.
Frequently Asked Questions
What happens at the cutoff frequency?
At the cutoff frequency (also known as the -3dB point), the output power is reduced by half, and the output voltage is approximately 70.7% of the input voltage. This marks the transition point between the passband and the stopband.
Why are low pass filters used?
They are widely used in audio engineering to remove high-frequency noise or hiss, in radio communications to filter out unwanted interference, and in power supplies to smooth out voltage ripples after rectification.