improved conversion efficiency and lower output ripple are achieved by a dc - to - dc converter that uses an h - bridge driver to alternately energize first and second inductors . by alternately energizing the first and second inductors , a higher switching frequency can be maintained allowing for the use of smaller inductors while reducing ripple in the output voltage . the reduced ripple in turn reduces the need for filtering . additionally , the first and second inductors are wound about a common core such that a mutual inductance exists therebetween . the mutual inductance results in trapezoidal currents in each inductor instead of the typical sawtooth waveforms . this results in still lower ripple in the output voltage .