Design of Power Efficient and High Slew Rate Class AB OPAMP

Abstract

The paper deals with aim to design an OPAMP of Class AB to achieve high power efficiency and slew rate. To have high slew rate the focus of the proposed work as high slew rate contributes to the fast and dynamic output response. Power efficiency is driving factor from MOORE’S law. A Push pull OPAMP with current replicating branch is used to achieve symmetrical wave with high slew rate. Adaptive biasing is another technique employed to increase the slew rate. According to the Moore’s law, increase in power takes place in adaptive biasing due to increase in transistors, but the proposed circuit is best tradeoff between slew rate and power efficient factors. The existing work could only increase the slew rate by 4 to 5 times, but our proposed work increases it even further compared to the existing work, at the same time it results in decrease of power. In this work we are combining two techniques, namely adaptive biasing and current replicating branch which combine to result in better slew rate without increase in power. The proposed work is implemented with Cadence Virtuoso tool.