Calculators / Passive filter and Bode plot

Passive filter and Bode plot

RC, RL, LC and RLC filters, low-pass to band-stop, with the magnitude and phase plots drawn as you type. Fit the values to an E-series and see what the rounding did to the response.

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Filter Design Parameters

filter_alt Filter Type & Topology

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Filter Response

Component Topology

settings_input_component Component Values

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Resistance (R) Ω

Capacitance (C) F

Inductance (L) H

show_chart Frequency Range

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Start Hz

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End Hz

Range: any value > 0 Hz up to 100 GHz (1×10¹¹ Hz). Logarithmic sweep with 500 data points.

Sweep Points

precision_manufacturing EIA Value Fitting

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Preferred Series

Cutoff / Center Freq
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Quality Factor (Q)

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Damping Ratio (ζ)

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ω₀ (Angular)

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-3 dB Bandwidth

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Rolloff Slope

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Bode Magnitude Plot

Gain (dB) vs. frequency on a logarithmic scale. Orange = ideal, green = EIA-fitted.

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Bode Phase Plot

Phase shift (degrees) vs. frequency on a logarithmic scale. Orange = ideal, green = EIA-fitted.

functions Transfer Functions & Key Equations

f_c= 1 / (2π·R·C) [RC Low-Pass] H(s)= 1 / (1 + s·R·C) |H(jω)|= 1 / √(1 + (ω·R·C)²) ∠H(jω)= −arctan(ω·R·C) Q= (1/R)·√(L/C) [RLC] ζ= R/(2)·√(C/L) = 1/(2·Q) BW= f₀ / Q [second-order]

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These tools and articles give theoretical estimates for educational purposes. Real results depend on component tolerances, parasitics and thermal conditions.