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Wide-Band CDMA Distortion Characteristics of an AlGaAs/InGaAs/AlGaAs Heterojunction FET under Various Quiescent Drain Current Operations
Gary HAU Takeshi B. NISHIMURA Naotaka IWATA
IEICE TRANSACTIONS on Electronics
Publication Date: 1999/11/25
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on High-Frequency/High-Speed Devices for Information and Communication Systems in the 21st Century)
Category: RF Power Devices
FET, microwave, amplifier, distortion, simulation, W-CDMA,
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Wide-band CDMA (W-CDMA) distortion characteristics of a fabricated double-doped heterojunction FET (HJFET) are presented. Measured results demonstrate that the first and second adjacent channel W-CDMA adjacent channel leakage power ratios (ACPRs) of the HJFET are correlated to the third- and fifth-order intermodulation (IM3 and IM5) distortions respectively under various quiescent drain current operation (Iq). A first channel ACPR dip phenomenon is observed under a low Iq condition, resulting in improved power added efficiency. Due to its close correlation to the IM3 distortion, the ACPR dip phenomenon is explained in terms of the similar IM3 characteristic. Simulated results reveal that the dip is a consequence of the cancellation of distortions generated by the third- and fifth-order nonlinearities at the IM3 frequency. The conditions for the cancellation are detailed.