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Cutoff Frequency Formula:
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The cutoff frequency (fc) is the frequency at which the output signal of a filter is reduced to half its power (-3 dB point). It represents the boundary between the passband and stopband in filter circuits.
The calculator uses the cutoff frequency formula:
Where:
Explanation: This formula calculates the -3 dB point for a simple RC (resistor-capacitor) filter circuit, where the output power drops to half of the input power.
Details: Accurate cutoff frequency calculation is crucial for designing electronic filters, audio systems, signal processing circuits, and communication systems where frequency separation is required.
Tips: Enter resistance in ohms (Ω) and capacitance in farads (F). All values must be valid positive numbers. For microfarads (μF), divide by 1,000,000 (10-6). For nanofarads (nF), divide by 1,000,000,000 (10-9).
Q1: What types of filters use this formula?
A: This formula applies to first-order RC low-pass and high-pass filters, which are the simplest types of electronic filters.
Q2: How does the cutoff frequency affect filter performance?
A: The cutoff frequency determines which frequencies are passed through (passband) and which are attenuated (stopband) by the filter circuit.
Q3: Can this formula be used for active filters?
A: While the basic principle is similar, active filters with operational amplifiers may have different transfer functions and cutoff frequency calculations.
Q4: What is the relationship between time constant and cutoff frequency?
A: The time constant (τ = RC) is inversely related to the cutoff frequency (fc = 1/(2πτ)).
Q5: How accurate is this calculation for real-world components?
A: The calculation provides theoretical values. Real-world accuracy depends on component tolerances, temperature stability, and circuit parasitic elements.