This is a high-pass filter implemented using a resistor and a capacitor. A high-pass filter passes higher frequencies and attenuates lower frequencies. The input frequency keeps changing, sweeping up and down the spectrum to demonstrate the change in response. The capacitor passes higher frequencies, causing the output voltage to fluctuate more. Lower frequencies are blocked, and there is reduced current across the resistor, keeping the output voltage closer to ground.
The breakpoint (-3 dB point) is shown at the lower right, as "f.3db".
Next: High-Pass Filter response (RC)
Previous: Parallel Resonance
