Design Of Low Voltage And Low-Power Rail-to-Rail CMOS Operational Amplifier Based On Bulk-Driven

With the development of portable electronic products and deep sub-micron CMOS process technology, low-voltage and low-power analog circuit design techniques are becoming research hotspot. In the analog integrated circuit, one of the typical circuits is operational amplifier. Therefore, the design of low-voltage and low-power operational amplifier is very necessary.The thesis has done the widespread investigation and study to the CMOS operational amplifier, based on the absorption of these technologies, it designs a low voltage and low power rail-to-rail CMOS operational amplifier based on bulk-driven techniques.The input stage of operational amplifier adopt the bulk-driven NMOS tube and PMOS tube parallel supplementary differential input pair structure,which avoids the limitation of threshold voltage efficiently. For design of rail-to-rail stable transconductance input stage, a variety of stable transconductance methods were compared,and finally the bulk-driven redundant differential pairs was employed. The middle stage use the bulk-driven low voltage, wide swing cascode structure which is suitable to work in low voltage. An improved feed-forward class AB output stage is used to enhance the dynamic range of output voltage, without circuit power increase, and having a good high-freauency characteristic, and also ensure that the current of the output transistors to be controlled precisely and the output swing reaches rail to rail.The circuit is simulated by using PTM 0.18μm CMOS process model and Hspice simulation software. The simulation results show that the DC gain is 62.1 dB, the unity gain bandwidth is 2.2MHz, and the phase margin is 60°. The input common-mode range and the output swing both reach rail to rail. The common-mode rejection ratio and the power supply rejection ratio of the circuit are both high. The circuit operates normally in a low voltage of 0.8 V, and the static power consumption is only 65.9μW.