Portable devices powered by batteries have experienced a dramatic growth in the last several years. In particular, devices such as cellular phones, portable computers, cameras, camcorders, and cordless tools have given a remarkable impulse to the market. The advancements in the field of transistors and other electronic components have been impressive and have played a very important role in this development. The so-called Moore’s law states, in its widely accepted form, that ‘the number of transi