LC Filter Calculator
Calculate cutoff frequency and design LC filter circuits
LC Filter Design Calculator
Allows low frequencies to pass, blocks high frequencies
Inductor value in circuit
Capacitor value in circuit
Filter Design Results
Cutoff Frequency
Circuit Components
Reactances at Cutoff Frequency
Formula used: fc = 1 / (2π√LC)
Calculation: fc = 1 / (2π × √(1.000 mH × 1.000 μF))
Filter characteristics: Human hearing range (20 Hz - 20 kHz)
Filter Design Notes
Example Calculation
Example: Audio crossover filter at 1 kHz
Given:
• Target frequency: 1 kHz
• Available capacitor: 47 nF
• Filter type: Low-pass
Calculate Required Inductance
L = 1 / (4π²f²C)
L = 1 / (4π² × (1000)² × 47×10⁻⁹)
L = 1 / (4π² × 10⁶ × 47×10⁻⁹)
L = 1 / (1.855 × 10⁻³)
L ≈ 0.539 H = 539 mH
Formula Reference
Filter Types
Applications
Design Tips
Use standard component values for practical designs
Consider parasitic resistance and tolerance effects
LC filters have sharper roll-off than RC filters
Quality factor Q affects bandwidth and selectivity
Understanding LC Filter Circuits
How LC Filters Work
LC filters use the frequency-dependent behavior of inductors and capacitors to selectively pass or block certain frequencies. Inductors have higher impedance at high frequencies (XL = 2πfL), while capacitors have lower impedance at high frequencies (XC = 1/(2πfC)).
Filter Configurations
- •Low-pass: Inductor in series, capacitor in parallel
- •High-pass: Capacitor in series, inductor in parallel
- •Band-pass: Series or parallel resonant circuits
- •Band-stop: Combination circuits for notch filtering
Design Considerations
Frequency Response:
• Cutoff frequency: fc = 1/(2π√LC)
• Roll-off rate: -40 dB/decade
• Phase shift: 90° per pole
Component Selection:
• Standard component values (E12, E24 series)
• Component tolerances affect accuracy
• Parasitic resistance affects Q factor
Practical Applications
- Audio Systems: Speaker crossovers, equalizers
- RF Circuits: Antenna tuning, channel selection
- Power Electronics: EMI filters, noise suppression
- Signal Processing: Anti-aliasing, smoothing filters