The present invention concerns a signal generator circuit powered by a supply voltage and including flip flop means including a first input to which is connected a continuous input signal whose amplitude is defined, a second input to which is connected a clock signal whose duty cycle is defined, and a third, reset input, and outputting an output signal whose duty cycle is that of the clock signal and whose amplitude is that of the input signal, characterized in that said circuit further includes regulating means arranged to compare the output signal to a set point signal representative of the desired duty cycle and to deliver a control signal connected to the third input of the flip flop means so as to activate the reset to modify the duty cycle of the output signal.