Power squeeze [Portable system energy budget]

Careful thought is needed to design portable systems that have a strong mixed-signal component. The need to power a system purely from batteries puts severe constraints on the design in terms of energy consumption. We are seeing more portable systems appear, particularly in the medical, industrial and consumer markets. Cost and size considerations mean they often need custom silicon designing for them. But there are different trade-offs needed depending on where the bulk of the energy is consumed. For energy efficient designs, it is important to calculate the energy budget of a system including internal and external power dissipation, and also to consider the energy budget summed over the full operating cycle or lifetime.