Analog to Digital Converters are widely used in the field of VLSI and are mainly used in the applications like audio, instrumentation, seismic, voice etc which requires higher value of resolution. For such applications, ADC?s can be used based on Nyquist Rate modulators (where sampling is done with twice the sampling frequency) or Sigma-Delta modulators (where sampling is done with 15-20 times the sampling frequency). ADC based on sigma-delta modulators is attractive for VLSI implementation because they are not so sensitive of circuit non-idealities and component mismatch. However, issues such as clock jitter and excess loop delay become great challenges to the designer, especially at high sampling frequency. Special design should be applied to overcome these problems. Sigma-Delta modulator can be of different orders like 1st order, 2nd order etc and can be continuous time (less power consumption) or Discrete Time. This book demonstrates a Graphical User Interface (GUI) of 2nd order Sigma-Delta modulator which is used to check the non-idealities of the circuit. Here the model is based on the behavioral modeling of the parameters with the help of Matlab- Simulink.