ABSTRACT
The CMOS two-stage operational amplifier is mainly composed of two single stage amplifier: folded cascode amplifier and common source with the current source load. Usually, most of the gain of the circuit are provided by the differential input stage, it can improve noise performance and reduce input offset. (Yin & Bai, 2012). The second level generally uses the common source to compensate output swing and provide gain. Bias circuit can establish appropriate quiescent operation point for the transistor. In addition, the compensation technique is used to stabilize the closed-loop characteristics.
