Evaluation of coupled inductor VR (2006)
Today's microprocessor VR mostly has several phases. As an example, the VR in the picture below for server has 6 phases. Therefore, we can couple the 6 phases by different ways: 3 *2 phase coupled, 2 *3 phase coupled and 1 *6 phase coupled. Which one is the best?
From the output cap reduction (VR transient performance enhancement) point of view, the above question is investigated, firstly. It is found that there is a diminishing return point when the coupling phase number is increased. This diminishing return point is dictated by the VR steady state output voltage ripple requirement (see the following figure).
From the efficiency increase point of view, the above question is also investigated. A diminishing return point is also found when you increase the coupling phase number.