基于模拟退火算法的I/Q不平衡校正

零中频发射机架构是目前集成度最高的发射机架构之一，直流偏置不平衡和I/Q不平衡的问题会大大降低其发射效率，并且会产生显著的镜像干扰信号、本振泄露信号和与有用信号同频的干扰信号.为了解决零中频发射机架构的I/Q不平衡问题，提出利用发射机和接收机射频前端的反馈回路，在数字域使用模拟退火算法（SAA）对I/Q不平衡的补偿因子进行闭环搜索，提出I/Q不平衡校正的新方法.在Simulink软件中进行建模仿真，模拟结果表明，所提方法在不同强度的高斯白噪声条件下能够有效地对I/Q不平衡进行校正.在LMS7002M集成式收发芯片的基础上，搭建了所需要的零中频发射机校正实验平台.实验结果表明，所提方法具有良好的温度适应性和频率适应性，在-20~50℃的温度条件下，所提方法的平均镜像抑制度为-60.5 dBc；在1 600~2 400 MHz的频率条件下，平均镜像抑制度为-57.5 dBc.
Abstract: Zero intermediate frequency (Zero-IF) transmitter architecture is one of the most integrated transmitter architectures. However, the DC offset and I/Q imbalance, will not only greatly reduce the transmission efficiency, but also generate significant image interference signal, local oscillator leakage signal and interference signal with the same frequency as the useful signal. A new I/Q imbalance calibration method was proposed to solve the imbalance in the Zero-IF transmitter architecture. The feedback loop of the radio frequency front-end of the transmitter and the receiver was employed, and a closed loop search for the I/Q imbalance compensation factor using a simulated annealing algorithm (SAA) in the digital domain was applied to create the calibration method. The simulation results of this design in Simulink showed that the proposed method can effectively calibrate the I/Q imbalance under different intensities of additive Gaussian white noise. The required Zero-IF transmitter calibration experimental platform was buit based on the LMS7002M integrated transceiver chip. The experimental result showed that the proposed method had adaptability for temperature and frequency. The average image rejection reached -60.5 dBc at the temperature of -20~50℃, and the average image rejection reached -57.5 dBc under the frequency of 1 600~2 400 MHz.