The present invention discloses a frequency-hopping carrier generator, which comprises a current source, a ramp generator and a switch power amplifier. The current source generates a first current; the first current is output to the ramp generator. The output of the ramp generator is coupled to a capacitor to generate a ramp voltage. The ramp voltage is connected to a voltage detection/direction control device and a PWM module. The PWM module receives an audio input signal and generates a PWM signal. When receiving a ramp voltage, the voltage detection/direction control device outputs a control signal to the ramp generator and a counter. The counter is coupled to a digital-control current source. According to the value of the counter, the digital-control current source outputs a second current to the ramp generator. The second current is merged with the first current. The merged current is used to charge/discharge the capacitor. The input end of the switch power amplifier receives a signal from the PWM module and modulates the audio input signal to output a class-D signal.