This simulation demonstrates an RC low-pass filter with a cutoff frequency around 159 Hz, where it allows low-frequency signals to pass while attenuating higher frequencies. The circuit consists of a 1 kΩ resistor and a 1 µF capacitor. The input signal frequency varies from 100 Hz to 20 kHz. At frequencies below 159 Hz, the output (green waveform) follows the input (blue waveform) with minimal loss. As the input frequency increases, the capacitor’s reactance decreases, causing the output amplitu

This RC low-pass filter (R = 1 kΩ, C = 1 µF) is driven by the green sine input while the violet trace is the output across the capacitor; the input frequency is swept from ~100 Hz to 50 kHz. With a cutoff 159 Hz, the output closely follows the input at 100 Hz (little attenuation, near-zero phase lag). As frequency rises to fc , the output amplitude drops to about 0.707 of the input (-3 dB) and the phase lags by ~45°. Beyond fc, the amplitude rolls off at ~20 dB/decade: at ~1.6 kHz (≈10 × ) it’s

QUCS Getting Started Tutorial RC Low Pass Filter