For commonly used CMOS (complementary metaloxide

Chapter 24, Problem 24.53

(choose chapter or problem)

For commonly used CMOS (complementary metaloxide semiconductor) digital circuits, the charging of thecomponent capacitors C to their working potential differenceV accounts for the major contribution of its energyinput requirements. Thus, if a given logical operationrequires such circuitry to charge its capacitors N times, wecan assume that the operation requires an energy ofN($CV2). In the past 20 years, the capacitance in digitalcircuits has been reduced by a factor of about 20 and thevoltage to which these capacitors are charged has beenreduced from 5.0 V to 1.5 V. Also, present-day alkalinebatteries hold about five times the energy of older batteries.Two present-day AA alkaline cells, each of which measures1 cm diameter by 4 cm long, can power the logic circuitry ofa hand-held personal digital assistant (PDA) with its displayturned off for about two months. If an attempt was made toconstruct a similar PDA (i.e., same digital capabilities so Nremains constant) 20 years ago, how many (older) AAbatteries would have been required to power its digitalcircuitry for two months? Would this PDA fit in a pocket orpurse?