High Efficiency, High Linearity GaN HEMT Amplifiers for WiMAX Applications

Worldwide Interoperability for M i c r o w a v e Access, better known as WiMAX, is a standardsbased wireless technology for providing highspeed, last-mile broadband connectivity to homes and businesses as well as for mobile wireless networks. With the fixed version of WiMAX, based on IEEE 802.16-2004, transmissions can potentially carry data traffic over more than 30 miles (~50 km) in rural areas, 6 miles (~10 km) in suburban areas, and 3 miles (~5 km) in dense urban areas. The technology is seen as both complement and successor to Wi-Fi, which sends data over shorter distances. The fixed version of WiMAX can provide data rates up to 75 megabits per second (Mbps) per four-sector base station. WiMAX will be instrumental in bringing broadband wireless to homes and offices, providing the backhaul for Wi-Fi hotspots, and eventually connecting users to the Internet in places not covered by 802.11. In those parts of the world lacking a well developed wired infrastructure, 802.16 offers a practical way to extend service to many different parts of a country, such as China or India. WiMAX can bring broadband access into the homes and businesses of millions of people in rural and developing markets. Table 1 shows a summary of the various allocated frequencies for WiMAX worldwide including those bands that are already populated with other services. For example, WiMAX services that would use the so-called BRS (broadband radio services) band around 2.5 GHz may have to be compliant to transmitters that are co-located so there are strict FCC regulations (04-258) that require adherence. In general the average output powers required under either standard or proprietary modulation/data schemes are in the range of 1 to 4 watts for fixed access and 20 watts for mobile scenarios compliant to IEEE 802.16. In general transmitters need to adhere to both GaN HEMT power transistors are a key enabling technology for successful design of WiMAX radio systems. This article demonstrates the performance enhancements offered by new transistor products. System / Region Frequency Band (GHz)