With the rapid development of portable electronic devices and Internet of Things (IoT) technology

low-voltage

low-power analog integrated circuit design has become a current research focus. This paper presents an improved two-stage fully differential CMOS operational amplifier suitable for 0.8V supply voltage. To address the issues of insufficient gain

limited output swing

and poor common-mode feedback stability in conventional two-stage op-amps under low voltage

this paper employs bulk-driven technology combined with positive feedback mechanism in the input stage

effectively enhancing transconductance and DC gain; the output stage adopts a class AB push-pull structure

achieving near rail-to-rail output swing; meanwhile

an improved continuous-time common-mode feedback circuit is designed to improve the stability and response speed of the common-mode loop. Designed and simulated based on SMIC 0.13um CMOS process

the results show that: under 0.8V supply voltage and 10pF load capacitance

the op-amp achieves a DC gain of 82.5dB

unity-gain bandwidth of 45.6MHz

phase margin of 62.3 degrees

slew rate of 18.7V/us

static power consumption of only 26.4uW

and output swing up to 0.12V~0.68V. Compared with conventional structures

the op-amp designed in this paper exhibits superior overall performance under low-voltage conditions

making it suitable for low-voltage applications such as portable medical devices and wireless sensor nodes.