Butterworth Pi LC Low Pass Filter Calculator

The Butterworth filter is a type of electronic filter. It is characterized in that the frequency response curve in the passband is as flat as possible, without undulations, and gradually decreases to zero in the blocking band. On the Bode plot of the logarithmic diagonal frequency of the amplitude, starting from a certain corner frequency, the amplitude gradually decreases with the increase of the angular frequency, and tends to be negative infinity.

There are many types of low-pass filters, the most common ones being the Butterworth filter and the Chebyshev filter.

Enter value
Cutoff Frequency:
Impedance Z0:
Number of Components: (1-11)
Calculation results
Inductance: Capacitance:
Unit : Unit :
L1: C1:
L2: C2:
L3: C3:
L4: C4:
L5: C5:
The Butterworth type filter was first described by the British engineer Stephen Butterworth.

A PI filter is a filter that has a series element and two parallel elements connected in the shape of the Greek letter PI.

Butterworth filter are characterized by a constant gain (flat response) across the midband of the circuit and a 20 dB per decade roll-off rate for each pole contained in the circuit.

Butterworth filters are termed maximally flat magnitude response filters, optimized for gain flatness in the pass band. The attenuation is -3db at cutoff frequency. Above the cutoff frequency the attenuation is -20 db.

The Butterworth is the only filter that maintains same shape for higher orders whereas other varieties of filters (Bessel, Chebyshev, elliptic) have different shapes at higher orders.

A Low pass filter is a filter that passes low-frequency signals but attenuates signals with frequencies higher than the cutoff frequency.