Calculate the corner frequency of RC and LC filters and the roll-off they achieve.
Each filter order adds 20 dB per decade of roll-off, so a second-order filter falls at 40 dB per decade. Cutoff is conventionally the half-power point, 3 dB below the passband. Steeper filters need higher order, which costs components and introduces phase distortion and potential ringing near cutoff.
Filter Cutoff Frequency
RC: f_c = 1 ÷ (2πRC); LC: f_c = 1 ÷ (2π√(LC)); roll-off = 20n dB/decade
RC: f_c = 1 ÷ (2πRC); LC: f_c = 1 ÷ (2π√(LC)); roll-off = 20n dB/decade Each filter order adds 20 dB per decade of roll-off, so a second-order filter falls at 40 dB per decade. Cutoff is conventionally the half-power point, 3 dB below the passband.
Steeper filters need higher order, which costs components and introduces phase distortion and potential ringing near cutoff.
This calculator takes 4 inputs: Resistance, Capacitance, Inductance for an LC filter, Filter order. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.