Working to help cell-phone users take advantage of the limitless minutes now included in many calling plans, engineers have developed a device that can significantly improve the quality of the transmitted signal on even less battery power.

"When you've been talking on a cell phone for a long time, you can feel how hot it gets," said Zhenqiang 'Jack' Ma, an assistant professor of electrical and computer engineering at University of Wisconsin-Madison. "This kind of overheating has always been a barrier to improving wireless communications."

Wireless communications devices, such as cell phones or cordless computer keyboards, rely on a small electrical part called a power amplifier. The amplifier, composed of tiny energy cells, is responsible for sending signals. In the case of cell phones, it turns on when the user hits the "send" button.

Ma and his graduate students developed technology that could mark the next step in power amplification. After reading through dozens of scientific papers and analyzing heat transfer with power amplifiers housed in wireless communication devices, Ma and his students found a way to significantly reduce the rising temperatures inside amplifiers from the increased electrical current.