Comparative study of two CMOS operational amplifiers for high performance pipelined ADC

摘要

This paper explains the choices taken for the design of two full differential operational amplifiers (Op-Amps). These Op-Amps have been designed for a MDAC (Multiplying Digital-to-.Analog Converter) stage of a pipelined ADC (Analog to Digital Converter). It shows also the solutions found to reach high gain, wide bandwidth and short settling time, without degrading too much the output swing. First the Op-Amp specifications are extracted starting from the ADC architecture, the two structures tested are then presented and the motivations of the final topology choice are shown. It presents then the op amp schematic implementation, the simulation results with the 180nm TSMC design kit.