Behavior Modeling and Simulation of a High Resolution Modulator for ADSL applications

要模数转换问题的研究中,介绍了∑-△调制器的过采样和噪声整形技术,为提高转换精度和速率,提出了一个采用四阶级联结构和∑-△调制技术实现高精度的调制器的行为级模型,根据影响建模的各种非理想因素,对各种实际非理想因素(例如开关热噪声、时钟抖动、运放的有限直流增益等)通过优化系统参数之后,可以得到一个用于AdSl设计中的高精度∑-△调制器行为级模型。并在MATlAb下对其仿真验证,结果表明为实际设计提供了依据。调制器在基带带宽1.5MHz、24倍过采样率条件下,系统的信噪比达到87db,精确度可达14比特。This paper presents overshanping and noise-shanging techniques used in sigma-delta modulator.Behavior modeling and simulation of a high resolution Sigma-Delta modulator by using 4-rd Cascade and sigma-delta modulator technique for ADSL applications is presented.Analyzed the main non-ideal mechanisms affecting the performance of Sigma-Delta modulator(such as switch thermal noise,clock jitter,finite dc gain of OPA,etc)and optimized the coefficients of the system by using MATLAB SIMULINK.In condition of various actual non-ideal performance of Sigma-Delta,simulation results show that the modulator system can achieve a SNR higher than 87dB and 14 bits accuracy with an overshaping ratio of 24