Slew rate enhancement circuit and method and operational amplifier

The invention provides a slew rate enhancement circuit, which comprises a threshold detection module used for detecting whether the difference between two differential input voltages exceeds a set threshold and performing output control on a first current and a second current according to a detection result; the rising edge slew rate control module is used for discharging a grid capacitor of an output stage PMOS (P-channel Metal Oxide Semiconductor) tube of the operational amplifier based on the first current to reduce the grid voltage when the difference between the positive input voltage and the negative input voltage exceeds a set threshold value, so as to enhance the rising edge slew rate; and the falling edge slew rate control module is used for charging a grid capacitor of an output-stage NMOS (N-channel Metal Oxide Semiconductor) tube of the operational amplifier based on the second current to improve the grid voltage when the difference between the negative input voltage and the positive input voltage