Dither ADC LTC2208的原理仿真和应用  

Simulation and Application of Dither ADC LTC2208

作　　者：张岳华[1] 邢燕[1] 

机构地区：[1]南京电子技术研究所,南京210039

出　　处：《现代雷达》2010年第7期98-101,共4页Modern Radar

摘　　要：无杂散动态范围是模/数转换器的重要指标之一,模/数转换器的量化噪声会使之恶化;虽然可以通过提高模/数转换器的量化位数来增加无杂散动态范围,但在高速模/数转换器中这种增加是有限的。自带dither功能的模/数转换器-LTC2208可以在输入端加入一个小幅抖动,打破输人信号与采样时钟的固定相互关系,打乱模/数转换器量化器DNL的周期性规律,从而使量化噪声和输人信号不相关,使量化误差均匀地分布到所有的频率分量中,从而相当于一种白噪声,这样就大大地减小了量化误差对谐波分量的贡献,提高了模/数转换器的无杂散动态范围指标。该文从理论上分析了量化噪声对无杂散动态范围的影响,介绍了Dither功能对模/数转换器作用的原理,在经过Matlab仿真后,设计了实际的电路模块,验证了该功能可有效提高模/数转换器系统的无杂散动态范围性能。Spurious free dynamic rang（SFDR） is one important characteristic of analog/digit conversion（ADC）, which would be deteriorated by quantization noise. The increase of quantization bit can improve SFDR, but the improvement is limited in ADC. LTC2208, a new ADC with Dither function, can add a little Dither signal to input analog signal to break the fixed correlation between input signal and sample clock, and eliminate the periodicity of ADC DNL. Because of disrelation between input signal and quantization noise the quantization error is distributed equably to all frequency component, which means the quantization noise could be regarded as white noise and the contribution to harmonic contents is reduced greatly. Thus, SFDR of ADC is improved. In this paper, the influence of quantization noise to SFDR is analyzed, introduces Dither function to ADC is improved. After simulation by Matlab, the designed circuit is also presented, and be proven to be effective.

关 键 词：模/数转换器 无杂散动态范围 抖动 量化噪声 

分 类 号：TN792[电子电信—电路与系统]