In a system though the analog circuits occupy very less space but they require far more design time than the digital circuits. This is due to the fact that the number of performance measures of an analog circuit is more than those for digital circuits. Predicting and improving the performance, robustness and overall cost of such systems is a major concern in the process of automation. In the automation process, optimization of performances subjected to a verity of environmental constraints is a central task. In this chapter, efficient analog circuit sizing techniques and their optimization are surveyed.