The present disclosure provides a PWM circuit, a modulation method, and an electronic device, and relates to the field of communication technologies. In the PWM circuit, a control word providing circuit can generate, based on an obtained target duty cycle, two target frequency control words with a ratio of the target duty cycle, and output the two target frequency control words to a pulse generation circuit; and the pulse generation circuit can output a target pulse signal with the target duty cycle under the control of the two target frequency control words. Because the control word providing circuit can generate the target frequency control words based on the desired target duty cycle, the pulse generation circuit can reliably generate the pulse signal with the target duty cycle based on the target frequency control words. In this way, the PWM circuit can flexibly generate the pulse signal.