The next formula is used to calculate the inductance to be used in a filter. This values depends on the filter coefficient, the used capacitor, the output current and also the frequency of the AC applied to the filter.

**Formula 1 **

Filter inductance:

**Where:**

L is the inductance in henrys (H)

α is the filter coefficient

ω = 2 x π x f , where f is the frequency in hertz (Hz)

C is the capacitance in farads (F)

Note: We can define the quantity η as the filter efficiency and the value is given by the following formula:

**Formula 2 **

Efficiency:

η = 1 / α

**Where: **

α is the filter coefficient

η is the filter efficience