正交调制器时序问题的分析与优化

在工程应用中,由于调制数据时序不佳引起的数字正交调制器的IQ不平衡和相噪恶化问题,严重影响数字正交调制器的调制效果。由于在带有随机数据调制时,调制后中频带宽较大,使IQ不平衡和相噪恶化问题不易被发现。为了解决上述问题,以AD9957作为数字正交调制器工作时为例,引入固定输入、同相正弦输入和正交正弦输入3种信号对调制器输出进行测试,使IQ不平衡和相噪恶化的问题容易被发现,通过分析和优化时序,很好地解决了IQ不平衡和相噪恶化问题。

Timing Analysis and Optimization of Quadrature Modulator

Quadrature modulator is affected by the IQ imbalance and phase noise worse caused by the time sequence of modulator data in the project applications.When modulating with random data,the IF bandwidth is large after modulating,so the IQ imbalance and phase noise worse is not easy to find out.In this paper,in order to solve the above problem,with AD9957 working as quadrature modulator,the output of modulator using three kinds of input signals of static input,in-phase sinusoidal input and quadrature sinusoidal input is discussed,then timing is analyzed and optimized,and thus the IQ phase unbalance and phase noise of modulator are reduced.