What is the -3dB frequency?

-3dB frequency is where output power = half input power (voltage = 0.707 of input). Below f_c: low-pass passes signal. Above f_c: high-pass passes signal. At f_c: exactly -3dB attenuation.

What is the difference between Butterworth, Chebyshev and Bessel filters?

Butterworth: maximally flat passband, gradual rolloff. Chebyshev: sharper rolloff but ripple in passband. Bessel: maximally flat group delay (linear phase), best for pulse transmission. Choose based on application priority.

How do I achieve steeper rolloff?

Cascade identical or different filter stages. n-pole filter has n×20 dB/decade rolloff. 2-pole Butterworth -40 dB/decade; 4-pole -80 dB/decade. Each additional pole adds -20 dB/decade and 90° phase shift.

Filter Cutoff Frequency Calculator

Calculate -3dB cutoff frequency for RC, RL, LC, and active filters. LP: f_c = 1/(2πRC). HP: f_c = 1/(2πRC). Band-pass: center f₀ = 1/(2π√(LC)). Roll-off rate: 1st order -20dB/decade, 2nd order -40dB/decade.

2D stress state at a point. All stresses in MPa.

σx — Normal Stress X (MPa)

σy — Normal Stress Y (MPa)

τxy — Shear Stress (MPa)

⚙ Mechanical Note: Results are based on standard textbook formulas and ISO/AASHTO references. Always verify critical designs with applicable codes (ISO 898, AASHTO 1993, AISC, Eurocode 3) and a qualified engineer.

How to Use

Enter the values for the patient or scenario you are assessing. Calculate -3dB cutoff frequency for RC, RL, LC, and active filters. LP: f_c = 1/(2πRC). HP: f_c = 1/(2πRC). Band-pass: center f₀ = 1/(2π√(LC)). Roll-off rate: 1st order -20dB/decade, 2nd order -40dB/decade. Use the filter cutoff result to inform your clinical assessment.

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Frequently Asked Questions

What is the -3dB frequency?

What is the difference between Butterworth, Chebyshev and Bessel filters?

How do I achieve steeper rolloff?