利用DDS镜像频率的宽带信号源设计

Wide-Band Signal Generator Utilizing DDS Image Frequency Components

提出了一种新方法,利用DDS(直接数字频率合成)器件的镜像输出频率分量,实现了常规DDS合成器方案所无法实现的超越奈奎斯特频率限制的信号频率输出,且易于实现高精度的载波频率控制和数字调制功能;实验原型电路采用了ALC(自动电平控制)技术补偿镜像和基频分量的衰减,实现了10 Hz^500 MHz的宽带信号输出,带内波动小于1 dB。

A new technical approach has been proposed to extend the upper bound of DDS（Direct Digital Synthesizer） output frequency over Nyquist limit by utilizing image frequency components. Superior out- put frequency tuning resolution and digital modulation can be readily realized. Experimental results show that the fluctuation of output magnitude is less than 1 dB within 10 Hz＇-500 MHz output spectrum band- width of our prototype system, which adopted ALC（Automatic Level Control） technique to compensate for the roll-off magnitude response of image and fundamental components.