The availability of good analog process in CMOS process has provided promising resulted avenues for the implementation of this topology of converter with good accuracy and low power consumption.The “Design of SAR based ADC (10 bits)” is an SAR based analog to digital converter using R-2R digital to analog converter. The objective is to assess the development of 10 bit SAR based ADC in 0.35um CMOS process. It consists of design and integration of various blocks of SAR based ADC which comprises of: 10 bits R-2R DAC, Precision Comparator, SAR control logic. The methodology of design is a full custom design using Verilog-Spice.The various blocks of SAR ADC are designed and individually analyzed and tested. First, SAR control logic is designed and simulated and then test bench code for SAR control logic is written to verify the functionality of the design. Then, the digital to Analog Converter is designed and simulated.All the chapters start with the brief explanation.