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Complex gain predistortion in WCDMA power amplifiers with memory effects


Varahram, Pooria and Mohammady, Somayeh and Hamidon, Mohd Nizar and Mohd Sidek, Roslina and Khatun, Sabira (2010) Complex gain predistortion in WCDMA power amplifiers with memory effects. The International Arab Journal of Information Technology, 7 (3). pp. 333-341. ISSN 1683-3198


Power amplifiers are essential components in communication systems and are inherently nonlinear. The nonlinearity creates spectral growth beyond the signal bandwidth, which interferes with adjacent channels. It also causes distortions within the signal bandwidth, which decreases the bit error rate at the receiver. In digital predistortion system, an inverse characteristic of power amplifier is generated and its amplitude and phase are combined to the signal input. So the input signal is predistorted and the power amplifier response is corrected. This process has to be controlled at high accuracy to achieve a satisfactory compensation effect. The inverse characteristics are stored in a memory (look-up table) and this data are updated using an error that is produced by comparing the outputs of power amplifier with the input signals. In this paper a novel technique for compensating such effects is proposed. It is a combination of two techniques, memory polynomial predistortion and the gain based predistorter method. This method is compared with the other technique, memory polynomial method and validated using a 1.9 GHz 60W LDMOS power amplifier and various signals such as 2-carrier WCDMA with 10 MHz carrier spacing and 15 MHz bandwidth. Simulations and results show improvement in ACLR reduction and EVM with applying this method.

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Additional Metadata

Item Type: Article
Divisions: Faculty of Engineering
Publisher: Zarqa University
Keywords: Digital predistortion; Memory effects; ACLR; Power amplifier; WCDMA
Depositing User: Nabilah Mustapa
Date Deposited: 14 Aug 2018 07:12
Last Modified: 14 Aug 2018 07:12
URI: http://psasir.upm.edu.my/id/eprint/13724
Statistic Details: View Download Statistic

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