Conference Paper

A 330W distortion-cancelled Doherty 28V GaAsHJFET amplifier with 42% efficiency for W-CDMA base stations

NEC Compound Semicond. Devices, Ltd., Shiga
DOI: 10.1109/MWSYM.2006.249498 Conference: Microwave Symposium Digest, 2006. IEEE MTT-S International
Source: IEEE Xplore

ABSTRACT An L/S-band 330W distortion-cancelled Doherty GaAs FET amplifier has been successfully developed optimizing the main and the peak amplifiers load impedance shift. The amplifier employed a pair of 28V operation 150W GaAs heterojunction FETs. It demonstrated low third order intermodulation of -37dBc with a drain efficiency of 42% at an output power of 49dBm around 6dB back-off level under the two-carrier W-CDMA signals of 2.135GHz and 2.145GHz. To our knowledge, these represent the best results ever reported among the simple high power FET amplifiers for W-CDMA base stations. Moreover, we proposed the evaluation techniques to obtain each AM-AM and AM-PM characteristics of the main and the peak amplifiers in an operating Doherty amplifier, and for the first time, experimentally proved the distortion cancellation effect in the GaAs FET Doherty amplifier

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