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Wireless Communications and Mobile Computing
Volume 2018, Article ID 8712414, 8 pages
Research Article

A Novel Quadrature-Tracking Demodulator for LTE-A Applications

Department of Computer and Communication Engineering, National Kaohsiung First University of Science and Technology, 2 Jhuoyue Rd., Nanzih, Kaohsiung City 811, Taiwan

Correspondence should be addressed to Kang-Chun Peng; wt.ude.tsufkn@gkpretep

Received 27 July 2017; Accepted 2 December 2017; Published 2 January 2018

Academic Editor: Chaojiang Li

Copyright © 2018 Kang-Chun Peng and Chan-Hung Lee. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This work develops an advanced quadrature-tracking demodulation technique for coherently demodulating the orthogonal frequency-division multiplexing (OFDM) signal of LTE-A systems. To overcome the fact that traditional coherent demodulators are extremely sensitive to the quadrature imbalance of a system, especially an OFDM system, the proposed architecture uses a novel quadrature phase-locked loop (QPLL) to track simultaneously the in phase (I-phase) and the quadrature phase (Q-phase) of the received signal. This advanced quadrature-tracking demodulator is realized using TSMC 0.18 μm CMOS technology and hybrid circuits. Experimental results indicate that the developed quadrature-tracking demodulator, which operates at 2.1~2.5 GHz, can effectively demodulate an 18 Mbps LTE-A signal, even with a 15 degree quadrature imbalance.