THE WIMAX STANDARD was spawned to enable high-data-rate wireless communications over long distances. WiMAX applications must therefore work under high-power conditions while satisfying tough efficiency and linearity requirements. To meet these needs, a high-electron mobility transistor (HEMT) places its roots in gallium nitride (GaN). The 15-W transistor, dubbed the CGH27015, features 14.5 dB of small-signal gain and 2-percent error vector magnitude (EVM) under orthogonal-frequency-division-multiplexing (OFDM) modulation when operated at 28 V. Over the frequency range of 2.3 to 2.9 GHz, this transistor typically produces 2.5 W of average output power and 24-percent drain efficiency. When compared with traditional technologies like silicon LDMOS or GaAs under WiMAX signals and requirements (802.16-2004), such performance supposedly translates into a 30-percent improvement in device efficiency.
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