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研究了一种基于混频器和低通滤波器的调制型高速高精度ADC系统。从ADC系统的结构出发详细推导了系统的频率响应,给出了系统的失真函数和混叠函数。从完全重构条件和子带信号频谱两个方面对调制型ADC系统和混合滤波器ADC系统进行了对比分析,提出了理想情况下两种系统在功能上等价的观点。最后对系统的功能进行了仿真验证,结果表明:调制型高速高精度ADC系统能克服系统受单片ADC芯片模拟输入带宽制约的问题,能广泛适用于高精度仪器仪表、软件无线电、宽带雷达等领域。
A high speed and high precision ADC system based on mixer and low pass filter is studied. From the structure of ADC system, the frequency response of the system is deduced in detail, and the distortion and aliasing functions of the system are given. The modulation ADC system and hybrid filter ADC system are compared from two aspects of the complete reconstruction condition and the sub-band signal spectrum, and the two systems are equivalent in function in the ideal case. Finally, the function of the system is verified by simulation. The results show that the modulation-type high-speed and high-precision ADC system can overcome the problem that the system is limited by the analog input bandwidth of the single chip ADC chip, and can be widely applied to high precision instrumentation, software radio, field.