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Influence of Frequency Characteristics of RF Circuits in Digital Predistortion Type Linearizer System on Adjacent Channel Leakage Ratio for W-CDMA Power Amplifier
Takeshi TAKANO Toru MANIWA Yasuyuki OISHI Kiyomichi ARAKI
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2004/02/01
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
digital predistortion, linearizer, W-CDMA, power amplifier, ACLR,
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In recent years, digital predistortion linearizers have been used in power amplifiers for mobile communications because they are simpler and provide higher power efficiency than conventional feedforward systems. However, in systems that cover a wider frequency band, it is impossible to disregard the frequency characteristics of their various parameters since the degradation that can result causes a decline in output power efficiency which is the most important property of a power amplifier. To date, no detailed studies have been carried out on predistortion compensation systems. Thus, we focused our research on these systems and in this paper we report the simulation and experimental results we obtained for clarifying these effects. In our experiments, we used a W-CDMA power amplifier to determine how much the distortion compensation effect is degraded by the frequency characteristics of analog RF circuits. The results of experiments to determine the relationship between the ACLR (Adjacent Channel Leakage power Ratio) and power efficiency are also reported.