Design And Optimization Of Folded Cascode CMOS Operational Amplifier

With the continuous development of the integrated circuit technology, high-performanceoperational amplifiers are widely used, they have been the core modules of analog integratedcircuits and mixed-signal integrated circuit. Integrated operational amplifier, referred as OpAmps, it has been widely used in analog computing, signal processing, D/A and A/Dconverter, as well as active filtering, and many other aspects. They were known as "universalintegrated circuit".This paper will design a folded cascode CMOS operational amplifier. The folded cascodecircuit can not only increase the gain, increase the power supply voltage noise rejectioncapability, and also allow self-compensation at the output. Compared to the telescopestructure, folded cascode circuit can increase the output swing of the circuit, and makes thecircuit more suitable for a unity gain buffer.In this design, firstly we compared the structure and properties of telescope and cascadeoperational amplifier. And then established the basic structure of the circuit, the foldedcascode operational amplifier structure. It can achieve the operational amplifier’s basicfunctions and parameters of the target. Then we repeatedly adjust the design parameters of thetransistors in a series of simulation and modeling, such as circuit performance andsimulation results in the Tanner EDA software, refer to the DC gain and AC gain, noise, andCMRR. Above this， we make the final the circuit parameters of the folded cascodeoperational amplifier be more reasonable and more optimized.