A ripple suppression circuit, comprising: a first diode; a first input port, configured to receive an input voltage via the first diode; a first output port, configured to output an output voltage; a first capacitor, configured to be connected between the first input port and a ground port; a first transistor, configured to be connected between the first input port and the first output port; a second diode and a second capacitor, configured to be connected in series between the first input port and the ground port; a second transistor, configured to be coupled between a base of the first transistor and a connecting node of the second diode and the second capacitor; a third capacitor, configured to be connected between a base of the second transistor and the ground port; and a voltage control circuit configured to be connected to the base of the second transistor, wherein when the input voltage drops to a minimum value, the voltage control circuit is configured to make a voltage of the base of the second transistor to be higher than the input voltage, and the output voltage to be equal to the minimum value, characterized in that the voltage control circuit comprises: a fourth capacitor, configured to be coupled between the ground port and the connecting node of the second diode and the second capacitor; a fifth diode and a sixth diode, configured to be reversely coupled in series between the first input port and the fourth capacitor, a cathode of the sixth diode is connected to the first port, an anode of the fifth diode is coupled to the fourth capacitor; a comparator, configured to compare the voltage at the base of the second transistor with the voltage of the anode of the fifth diode, and output a comparison result; and an optical coupler, configured to be controlled by the comparison result, wherein when the voltage at the base of the second transistor is lower than the voltage of the anode of the fifth diode, the optical coupler is configured to couple the base of the second transistor to the anode of the fifth diode. a first diode; a first input port, configured to receive an input voltage via the first diode; a first output port, configured to output an output voltage; a first capacitor, configured to be connected between the first input port and a ground port; a first transistor, configured to be connected between the first input port and the first output port; a second diode and a second capacitor, configured to be connected in series between the first input port and the ground port; a second transistor, configured to be coupled between a base of the first transistor and a connecting node of the second diode and the second capacitor; a third capacitor, configured to be connected between a base of the second transistor and the ground port; and a voltage control circuit configured to be connected to the base of the second transistor, wherein when the input voltage drops to a minimum value, the voltage control circuit is configured to make a voltage of the base of the second transistor to be higher than the input voltage, and the output voltage to be equal to the minimum value, a fourth capacitor, configured to be coupled between the ground port and the connecting node of the second diode and the second capacitor; a fifth diode and a sixth diode, configured to be reversely coupled in series between the first input port and the fourth capacitor, a cathode of the sixth diode is connected to the first port, an anode of the fifth diode is coupled to the fourth capacitor; a comparator, configured to compare the voltage at the base of the second transistor with the voltage of the anode of the fifth diode, and output a comparison result; and an optical coupler, configured to be controlled by the comparison result, wherein when the voltage at the base of the second transistor is lower than the voltage of the anode of the fifth diode, the optical coupler is configured to couple the base of the second transistor to the anode of the fifth diode.