PreBuild Engineering
PCB calculators / Circuit design
Free tool · PreBuild Engineering

RC low-pass filter calculator

Design an anti-aliasing or debounce filter and check how much it attenuates at a given frequency.

Inputs

kΩ
nF
Hz

Result

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Why it matters

RC filters set ADC anti-aliasing, debounce buttons and clean up PWM. Too slow a filter breaks sampling and response time; too fast a filter does nothing.

Formula

f_c = 1 / (2π · R · C) τ = R · C |H(f)| = 1 / √(1 + (f / f_c)²)

Design tips

  • Large R on an ADC input slows the charging of the ADC's sample capacitor: check the MCU's source-impedance limit.

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Results are engineering estimates from standard formulas and published approximations. Always confirm against component datasheets, your fabricator's capabilities and, for critical designs, simulation or measurement.