The popularity of cellular phones and other wireless communication means is growing rapidly. The number of cellular phone subscribers in Japan exceeded 100 million in 2007, which suggests many Japanese people currently use two or more cellular phones. The introduction of flatrate data communication and other user-beneficial services has fostered the steady increase of data communication traffic by cellular phones. According to a demand forecast, worldwide demand for data communication traffic in 2015 will reach 10 times the level seen in 2008 (1). In response to the increasing demand for communication traffic, cellular phone operators are planning to replace their second-generation cellular systems with third-generation or its successor. One major problem associated with upgrading current cellular system to next-generation system is an increase in power consumption of the equipment caused by increasing data rate and broadening bandwidth. Cellular phone operators consume most of the power to operate base stations, switchboards and other communication equipment. Their power consumption accounts for some 10% of that consumed in the communications sector. Taking these situations into account, we have developed a new technology to radically improve the efficiency of highpower amplifiers that consume most of the power required by cellular phone base stations. Using this technology, we manufactured high-power amplifiers and installed them in a remote radio head (RRH) for use in a cellular phone base station. The manufactured remote radio head achieved the highest level of efficiency in the industry. This paper discusses the details of the new technology. 2. Technology for Improving High-Power Amplifier Efficiency