Anyone who uses a cell phone or a WiFi laptop knows the irritation of a dead-battery surprise. But now researchers at the University of Rochester have broken a barrier in wireless chip design that uses a tenth as much battery power as current designs and, better yet, will use much less in emerging wireless devices of the future.
Hui Wu, professor of electrical and computer engineering at the University of Rochester, a pioneer in a circuit design called an “injection locked frequency divider,” or ILFD, has solved the last hurdle to making the new method work. Wireless chip manufacturers have been aware of ILFD and its ability to ensure accurate data transfer using much less energy than traditional digital methods, but the technique had two fatal flaws: it could not handle a wide range of frequencies, and could not ensure a fine enough resolution within that range. Wu, together with Ali Hajimiri, associate professor of electrical engineering at California Institute of Technology, surmounted the first problem in 2001, and has now found a solution for the latter.
Wu’s new design makes the practical application of ILFDs possible. He introduced a new topology into this circuitry—instead of the old three-transistor design, his has five transistors—creating what he calls “differential mixing.” The new circuitry topology allows the ILFD to divide by three as well as two.
This tiny change has huge ramifications. A circuit design that can divide by two or three can, for instance, divide 9,999 clock pulses by two, and the 10,000th by 3, giving an average of 2.0001, which could be the frequency at which the cell phone is trying to communicate. Should the phone need to communicate at 2.0002 gigahertz, the ILFD could divide 9,998 clock pulses by two, and the 9,999th and 10,000th by three, yielding an average of 2.0002. By varying how many clock pulses are divided by two or by three, any frequency can be selected, making the power-saving ILFD method viable for the first time.
Sometimes, I wish cell phones ran so hot and inefficient you’d have to turn them off every few minutes to cool down!
any word on when we will see this in laptops?
I hope they do not plan to charge very much to license this technology because Cell Phone manufacturers do not care about battery life. If they did, they would have started using switching power supplies years ago instead of continuing to use linear supplies. By using a switcher instead of a linear supply they could more double the current battery life of a phone. Thats in real life, not just theory.
There are three thing’s that that Cell Phone Manufacturers really care about when designing their phones: Cost, Integration and Customer Demand. Cost should be obvious, but these guys take it to an extreem (remember most phones will be “given away”. Yes I know we reallly pay for them, but thats not how the Cell Phone Companies treat it). Integration goes hand in hand with cost, the more things that can be squeezed into one chip, the cheaper it is to build the phone (This is why the one chip cell phone is the holy grail for these guys). Integration is more important to these guys from a cost of assembly aspect than it is for reduction in size.
Customer Demand is really the main reason why new features get added to cell phones, but we need to realize who the real customer is. It is not the individual consumer who uses the phone, rather it is the Cell Phone Companies which buy these phones in the millions and then gives them to their customers with strings attached. Cell Phone Companies do not care about battery life (if they did, cell phones would not have camera’s, MP3 players or play games). They mainly care about getting the customer to use as many of their services as they can, even if they have to force them into it. In fact, one could argue that Cell Phone Companies prefer keeping battery life at about 2 hours of talk time per charge (for average use) because it forces a constant recharging of the battery; making sure that it will wear out within two years. At that point, the customer becomes dissatisfied with their phone and is much more willing to sign another agreement to tie themselves to the Cell Phone Company for another “Free” phone, which now has more “Features” which force the user to spend more money on the Cell Phone Companies services.
Back to this article; If this technology does not make it into Cell Phones (for the reasons stated above), it still looks great for Wireless PDA’s and network adaptors. The problem is that in those markets, battery life is often less compelling as they are using larger batteries. These are also much smaller markets.