Design a band-stop or notch filter to reject a specific frequency band.
A notch filter needs high Q to reject a narrow band without affecting nearby wanted signals. Mains hum rejection at 50 or 60 Hz is the most common application. Too low a Q removes wanted signal along with the interference, while too high a Q makes the notch sensitive to component drift and frequency variation.
Band Stop Filter
Notch frequency = √(f_L f_H); Q = f₀ ÷ stop bandwidth; C = 1 ÷ ((2πf₀)² L)
Notch frequency = √(f_L f_H); Q = f₀ ÷ stop bandwidth; C = 1 ÷ ((2πf₀)² L) A notch filter needs high Q to reject a narrow band without affecting nearby wanted signals. Mains hum rejection at 50 or 60 Hz is the most common application.
Too low a Q removes wanted signal along with the interference, while too high a Q makes the notch sensitive to component drift and frequency variation.
This calculator takes 4 inputs: Lower cutoff frequency, Upper cutoff frequency, Signal frequency, Inductance available. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.