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Butterworth Filter Calculator
Calculate ideal Butterworth prototype values and scaled LC components for low-pass or high-pass filters using order, cutoff frequency, and impedance.
Input Parameters
Results
Equations Used
Butterworth Prototype: gk = 2 × sin((2k - 1)π / (2n))
Low-Pass Scaling: Series L = gkR/ωc, Shunt C = gk/(Rωc)
High-Pass Scaling: Series C = 1/(gkRωc), Shunt L = R/(gkωc)
Ideal Roll-off: 20n dB/decade where n is filter order.
Frequently Asked Questions (FAQ)
Q1: What does a Butterworth filter calculator do?
It calculates ideal normalized prototype values and scaled LC component values for Butterworth filters.
Q2: Why choose Butterworth response?
Butterworth filters are maximally flat in the passband and avoid ripple in the ideal response.
Q3: What does filter order change?
Higher order increases roll-off steepness but also increases component count and sensitivity.
Q4: Can I use this directly for RF PCB design?
Use it as a starting point. RF implementation needs component models, parasitic extraction, layout control, and measurement.
Q5: Does this include source and load termination?
It assumes a normalized doubly terminated prototype scaled to the entered impedance.
