Low-noise operational amplifier capable of driving capacitive heavy loads and suitable for image sensor

The invention discloses a low-noise operational amplifier capable of driving capacitive heavy loads and suitable for an image sensor. The operational amplifier comprises twenty-four MOS (Metal Oxide Semiconductor) transistors, namely, first to fourteenth PMOS (P-channel Metal Oxide Semiconductor) transistors M00, M01, M1, M2, M7, M8, M9, M10, M11, M12, M13, M14, M21 and M22 and first to tenth NMOS (N-channel Metal Oxide Semiconductor) transistors M3, M4, M5, M6, M15, M16, M17, M18, M19 and M20, a first capacitor Cm1 and a second capacitor Cm2 which are connected with each other, and a resistor Rm. The constructed multi-stage operational amplifier comprises three gain amplifying stages, two active feedback loops and a feed-forward path. The amplifier can drive heavy-load capacitors or resistors at relatively low noise under the conditions of low pressure and low power consumption.