In this paper, an operational amplifier with low-power consumption has been designed. Using the complementary differential pair for the input stage and the class AB structure for the output stage, the common-mode input range and output swing of the proposed circuit could achieved rail-to-rail. Based on TSMC 0.18μm CMOS process, using HSPICE 2008 software for circuit simulation, the results showed that the proposed op-amp has more than 100dB open loop gain, meanwhile the static power consumption is less than 300μw. The circuit's phase margin is 68 degrees, CMRR is 135dB and power supply rejection ratio is 63dB.
