Low power asynchronous digital signal processing

Over the past twenty years, the mobile phone has emerged from its early role as toy for a few wealthy technophiles to establish its current position as a true mass communication medium. Sales of mobile phone handsets are vast and rapidly increasing, with the number of subscribers having increased from 11m in 1990 to 180m people in 1999 . Part of this rapid growth can be attributed to the decrease in price of the handsets, to the point that mobile network operators are able to actually give away handsets, defraying the cost in the revenue gained from contract fees and call costs. The low unit price makes this market extremely competitive, with manufacturers vying with one another to find differentiating features that give their phones a competitive advantage over those of their rivals. However, one factor dominates when distinguishing between phones: the size and weight of the handset. This is largely controlled by the trade-off between battery size and battery lifetime, which itself is controlled by the power consumption of the circuitry within the handset. Licensing of radio bands for third-generation cellphones, supporting high bandwidth data transfer, have recently taken place with bids reaching unprecedented levels . The high commercial stakes and the imminent arrival of new high performance technologies therefore make mobile phones a very important application for low power circuit design.