直接正交上变频调制器的镜频抑制与本振泄漏对消技术研究

The Research on the Image Frequency Rejection and LO-leakage Cancellation of Direct Quadrature up-Converters

镜频干扰和本振泄漏是制约直接正交变频技术在无线通信收发信机中应用的主要技术瓶颈之一．通过分析直接正交上变频调制器中引起镜频干扰和本振泄漏的原因，利用逆向校正方法，给出了一种闭环反馈式正交基带信号预失真数字幅相平衡补偿电路，提出了一种通过调节基带信号的直流偏置实现本振泄漏对消的措施，提高了直接正交上变频器的镜频抑制和本振泄漏对消能力，并给出了在小型化CDMA发射机中的应用实例．

The image frequency interference and LO-leakage are the technical bottlenecks, which restrict the performance of the direct quadrature converter in wireless communication transceivers. Analyzed the reasons causing the image frequency interfer- ence and LO-leakage in the modulator,and provided a closed-loop feedback baseband quadrature signal pre-distortion circuit,based on the digital amplitude and phase balance compensation by using a reverse-correction method, and gave a circuit to achieve the I.D- leakage cancellation through adjusting the De bias of the baseband signals. Those increased the abilities of the image frequency re- jection and LO-leakage canceUation in the modulator, and applied in the design of a CDMA transmitter.