RC Filter (Low-pass / High-pass)

Analyze first-order RC filters in time and frequency domain

Calculator Mode

Analysis ModeCalculate f_c from known R and CDesign ModeFind R and C for target f_c

Parameters

Configure RC filter parameters

Filter Topology

Output across capacitor (charging curve)

Resistance

Capacitance

Input Voltage (V_in)

Results

Enter parameters to see RC filter calculation results.

RC High-pass Filter

High-pass filter: Output taken across the resistor. Passes high frequencies, attenuates low frequencies. Step response shows voltage decaying exponentially as capacitor charges. At cutoff frequency f_c = 1/(2πRC), magnitude is -3 dB and phase is +45°.

v_{out}(t) = V_{in} \cdot e^{-\frac{t}{\tau}}, \quad H(j\omega) = \frac{j\omega RC}{1 + j\omega RC}

Where:

v_{out}(t)

= Output voltage at time tV

V_{in}

= Input voltageV

R

= ResistanceΩ

C

= CapacitanceF

\tau = RC

= Time constants

f_c = \frac{1}{2\pi RC}

= Cutoff frequency (-3 dB point)Hz