Butterworth Tee LC Low Pass Filter Calculator

Enter value, select unit and click on calculate. Result will be displayed.

Cutoff Frequency:
Impedance Z0:
Number of Components:
(1-11)
Inductance: Capacitance:
Unit : Unit :
L1: C1:
L2: C2:
L3: C3:
L4: C4:
L5: C5:
L6:  

A Butterworth Tee LC Low-Pass Filter Calculator is a tool used to design a low-pass filter with a Butterworth response in a T-configuration using inductors (L) and capacitors (C). This type of filter is known for its maximally flat frequency response, meaning it has no ripples in the passband and provides a smooth, consistent attenuation.

Let's break down what it does:

Butterworth Response: The filter's gain decreases smoothly and predictably, with a roll-off of -20 dB/decade per pole after the cutoff frequency.
T-Configuration: The components are arranged in a "T" shape: two series inductors with a shunt capacitor between them for low-pass filtering.
LC Components:
L (Inductors): Block high-frequency signals.
C (Capacitor): Shunts high-frequency signals to the ground.
What the Calculator Does:
You input design parameters like:

Cutoff frequency (Fc) — where the signal starts to attenuate
Load impedance (Z) — like speaker or circuit input impedance
Order of the filter — the number of LC sections, determining steepness of attenuation
The calculator then outputs the values for the inductors and capacitors needed to achieve the Butterworth response. For a simple second-order (2-pole) filter, for instance: