A curve fitting circuit, an analog predistorter, and a radio frequency signal transmitter are disclosed. Each segmentation processing circuit in the curve fitting circuit generates a to-be-processed signal according to a intercepted part of a received signal, and generates q output signals according to the to-be-processed signal. Parts intercepted by different segmentation processing circuits are not exactly the same. Each first adder circuit in the curve fitting circuit receives one signal in the q output signals of each segmentation processing circuit, and obtains one output signal of the curve fitting circuit according to a sum of received n signals.