This project was an attempt to develop a Successive Approximation Analog to Digital Converter. The circuit conists of sample and hold circuit, a comparator, a SAR logic circuit and DAC, using Skywater130 technology.

The first step was to develop a CMOS inverter. A CMOS OP-amp was developed next. A CMOS switching circuit was developed next. This enabled the development of the sample and hold circuit. CMOS OP amp can also be used for comparator. The SAR logic is implemented using D flip flops. The D flip flop was developed next from CMOS. The SAR logic was constructed. A R-2R ladder DAC was developed next.

The CMOS has lot of offset voltages. A point to note during ngspice simulation is to always provide dc current path for capacitors and inductors. It was discovered that Skywater library must not be included more than once. This will lead to redefinition problems during simulation.

There are still offset issues that need to be resolved. The results do not match exactly.
