A Novel Quadrature‐Tracking Demodulator for LTE‐A Applications
Kang-Chun Peng, Chan-Hung Lee · Wireless Communications and Mobile Computing · 2018
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.