Voltage deviation of POL converter with two-stage output filter

Obtaining a very low output filter has become a vital requirement for most of telecommunications applications. One from the common and practical ways to obtain a low output voltage ripple is to add a second stage LC filter. However, this creates a problem for the converter dynamics. In this paper, the Point Of Load (POL) buck converter with a second-stage LC filter is analyzed form the dynamics prospective. The main target is to find the output voltage deviation at the load terminal as a function of the converter parameters where a second stage LC filter is connected. The new analysis determines the main effective parameters and so the design rules are provided for a better dynamic performance in addition to the designed low-output voltage ripple. Experimental data has confirmed the analysis with a good matching.