What does a pi filter inductor have at each end?

A pi filter is a type of analog filter used to smooth out the output of power supplies, particularly in the rectification process. Its name comes from the fact that the configuration resembles the letter "pi" (π) in the Greek alphabet.

In a typical pi filter, the inductor is positioned at the center of the circuit, with capacitors located at each end. These capacitors serve crucial roles in filtering out the high-frequency noise and ripple that might still be present in the DC output after rectification. By storing energy and releasing it as needed, the capacitors effectively absorb these fluctuations, leading to a more stable DC voltage.

The design of having capacitors on either end enables the pi filter to provide better attenuation of unwanted frequencies. The combination of the inductor and capacitors not only smooths out the voltage but also helps reduce the effects of load changes on the output voltage. The inductor reacts to changes in current, while the capacitors handle voltage smoothing, effectively working together to enhance power supply performance. Therefore, the presence of capacitors at each end of the inductor is fundamental to the pi filter's functionality.