RC Filter Calculator
Calculate cutoff frequency, resistance, and capacitance for RC low-pass and high-pass filters
Calculate RC Filter Parameters
Resistor value in the RC circuit
Capacitor value in the RC circuit
RC Filter Results
Formula used: fc = 1 / (2π × R × C)
Filter type: low-pass filter
Time constant: τ = R × C = 47.000 μs
Filter Analysis
Example Calculations
Audio Low-Pass Filter
Application: Remove high-frequency noise from audio signal
Resistance: 1.6 kΩ
Capacitance: 100 nF
Cutoff frequency: fc = 1/(2π × 1600 × 100×10⁻⁹) ≈ 995 Hz
RF High-Pass Filter
Application: Block DC and low frequencies in RF circuits
Resistance: 50 Ω
Capacitance: 3.2 nF
Cutoff frequency: fc = 1/(2π × 50 × 3.2×10⁻⁹) ≈ 995 kHz
Standard Component Values
Resistors (E12 Series)
Capacitors
Common Applications
Audio Systems
Anti-aliasing, noise reduction
Power Supplies
Ripple filtering, decoupling
Signal Processing
Bandwidth limiting, conditioning
RF Circuits
DC blocking, coupling
Timing Circuits
Delay, integration
Understanding RC Filters
What is an RC Filter?
An RC filter is a simple electronic circuit consisting of a resistor (R) and capacitor (C) that can filter frequencies from an input signal. The arrangement of these components determines whether the filter passes low frequencies (low-pass) or high frequencies (high-pass).
How RC Filters Work
- •Capacitor impedance varies with frequency: Xc = 1/(2πfC)
- •Resistor impedance remains constant: XR = R
- •Filter behavior depends on component arrangement
- •Cutoff frequency occurs at -3dB attenuation point
Filter Types
Low-Pass Filter
Allows low frequencies to pass while attenuating high frequencies.
Configuration: Resistor in series, capacitor to ground
High-Pass Filter
Allows high frequencies to pass while attenuating low frequencies.
Configuration: Capacitor in series, resistor to ground
Note: The cutoff frequency formula fc = 1/(2πRC) applies to both filter types.
Key Parameters
Cutoff Frequency (fc)
Frequency at which the output power is half the input power (-3dB point). Calculated as fc = 1/(2πRC).
Time Constant (τ)
Product of resistance and capacitance (τ = RC). Determines the response speed of the filter to step changes.
Roll-off Rate
RC filters have a roll-off rate of 20dB/decade (6dB/octave) beyond the cutoff frequency.