Efficient Digital Compensation Technique for Path Imbalances in LINC Transmitters Using Complex Gain and Linear Model

Hyunchul KU  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E95-C   No.7   pp.1222-1225
Publication Date: 2012/07/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E95.C.1222
Print ISSN: 0916-8516
Type of Manuscript: BRIEF PAPER
Category: 
Keyword: 
error vector magnitude,  LINC,  path imbalance,  digital compensator,  complex gain,  

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Summary: 
In this paper, a simple and efficient design scheme for digital compensation of path imbalances in linear amplification with nonlinear component (LINC) transmitters is proposed to reduce signal distortion. For the LINC transmitters including path imbalances, an error vector magnitude (EVM) is analyzed and an optimal complex gain that minimizes the EVM is extracted. In addition, a straight-forward compensation scheme for the path imbalances is proposed using a least square method for complex gains of each radio frequency path. The effectiveness of the proposed method is compared with the other digital compensation methods. A LINC transmitter with multi-level quadrature amplitude modulation input signals is experimented to verify the performance of the suggested scheme. The proposed compensator can reduce the EVM and the adjacent channel power ratio of the output signals less than 2% and 45 dBc, respectively.