The values of the L and C elements determine the cutoff frequencies for these circuits. The circuits below show the standard configurations as a low pass or high pass filter. The standard implementation is as a low pass filter, allowing this circuit to be used as a higher order filter for the input to DC power supplies. As these filters include three L or C elements, these filters are 3rd order in nature and provide strong rolloff above the cutoff (~20 dB/decade). Here’s what you need to know about pi filter design and simulation.Ī pi filter is a type of LC filter, where the LC filters are arranged to resemble the Greek letter “pi.” A pi filter can be configured as a high pass filter or a low pass filter. The design principles for pi filter circuits are deceptively simple, and these filters can be easily adapted for many applications using discrete components. If you’re looking to a simple higher order passive filter for use in impedance matching, EMI filtering, and power regulation, a pi filter provides strong rolloff without active circuit elements. Although integration of filter circuits into many SoCs is simplifying circuit design and layout tasks, filters made from discrete elements are not going away and find their home in many important circuit designs. These filter circuits are critical in many applications, but they are quite simple to design. Impedance matching, power regulation, EMI filtering… the applications of different filter circuits are varied. If you need a simple higher order passive filter, a pi filter is a good choice.

T pi filters design