First-Order Filter Comparison
Description
This MicroSim compares all four first-order filter topologies — RC Low-Pass, RC High-Pass, RL Low-Pass, and RL High-Pass — on the same Bode plot.
Key insight: RC and RL filters with the same cutoff frequency produce identical frequency response curves. The difference is only in which components are used.
| Filter | Output tap | Cutoff formula |
|---|---|---|
| RC Low-Pass | Across C | \(f_c = \frac{1}{2\pi RC}\) |
| RC High-Pass | Across R | \(f_c = \frac{1}{2\pi RC}\) |
| RL Low-Pass | Across R | \(f_c = \frac{R}{2\pi L}\) |
| RL High-Pass | Across L | \(f_c = \frac{R}{2\pi L}\) |
Controls: - f\(_c\) slider: Set target cutoff frequency (100 Hz – 10 kHz) - R slider: Set resistance (100 Ω – 10 kΩ); C and L are auto-calculated - Toggle buttons: Show all four filters, RC only, or RL only - Component table: Displays the calculated R, C, and L values for each topology