A High Precision Cmos Op Amp Design

In recent years, as a result of the electronic test survey product in the medical field, the automobile electron system, the military astronautics domain's widespread application, it's eager for the use of the CMOS low voltages high accuracy operational amplifier to be advantageous for the integrated conformity to make SOC to the rear end chip. Its need to magnify processing for the weak signal in the test survey, therefore it became necessity that the high accuracy operational amplifier is studied inevitably, which advanced the development of the high accuracy operational amplifier.The thesis has done the widespread investigation and study to the domestic and foreign technologies of analogy low voltage, and analyzed the principles of work, merits and shortcomings of these technologies. It designs a high accuracy operational amplifier. This article mainly aim at reduces the input offset voltage to launch the research and design operational amplifier. The structure of input stage adopted folded-cascode. In order to reduce the twinkle noise, the input differential stage used PMOS tube. Simultaneously the bias current mirror load of folded- cascode differential input stage was offered by the wide swing cascade which can run under low voltage normally; The PMOS tube common source amplifier was adopted in the gain stage for the sake of reducing the twinkle noise ; When designing output stage, in order to enhance the efficiency, it uses the push-pull common source stage amplifier as the output stage, the output voltage swing basically reached the supply voltage; The normal source of the thesis adopted use the traditional normal current source based on the operational amplifier; In order to work stability the amplifier uses the Miller compensate technology with a adjusting zero resistance to compensate the operational amplifier.The entire circuit uses the standard's 2.0um CMOS technological parameter model to carry on the design. After the simulation tool of SPICE of or CAD , the result indicated that the offset voltage achieves 21. 7uV, the direct-current open-loop gain, the unit gain band width and the common rejection ratio respectively achieves 87dB, 1.44MHz and 150 dB, each technical specification satisfies the design requirements under the direct power of±2. 0V , besides ,the power consumption is 46mW . The layout design uses the Tanner layout software, uses optimized the layout design technique to carry on the design, the area of layout is 540×560um~2.This operational amplifier can use in the measuring instrument, the control system, the medical field and so on face to the test and the measuring instrument, the automobile electron system and in the industrial control system's electronic products.