Current sensing circuit for generating sensed current signal with average value being constant under different input voltages of direct current to direct current converter and associated current-mode control circuit

A current-mode control circuit of a direct current to direct current (DC-to-DC) converter comprising:

• an error amplifier circuit, arranged to receive a feedback voltage of the DC-to-DC converter and a reference voltage, and generate an error signal according to the feedback voltage and the reference voltage;
• a current sensing circuit, comprising:
• an inductor current sensing circuit, arranged to sense an inductor current of the DC-to-DC converter to generate a first sensed current signal, wherein an average value of the first sensed current signal is not a constant under different input voltages of the DC-to-DC converter;
• and
• a processing circuit, arranged to generate a second sensed current signal, wherein the first sensed current signal is involved in generation of the second sensed current signal, and an average value of the second sensed current signal is a constant under said different input voltages of the DC-to-DC converter;
• a ramp generator circuit, arranged to generate a ramp signal;
• a first combining circuit, arranged to combine the second sensed current signal and the ramp signal to generate a summing signal;
• and
• a comparator circuit, arranged to receive the error signal and the summing signal, and generate a control signal according to the error signal and the summing signal, wherein an output voltage of the DC-to-DC converter depends on the control signal.