VoIP subscriber line interface boost circuit

The utility model relates to the technical field of VOIP telephones, in particular to a VoIP subscriber line interface booster circuit, which comprises a first-stage Cuk converter, a second-stage Cuk converter and a third-stage Cuk converter, and is characterized in that the first-stage Cuk converter comprises an inductor L3, a switch triode Q1, an energy storage capacitor C16, an inductor L4, a diode D2, a filter capacitor C6, a filter capacitor C7 and a filter capacitor C18; according to the VoIP subscriber line interface booster circuit designed by the utility model, the three stages of Cuk converters are combined and superposed to be used for the VoIP subscriber line interface booster circuit, and the first negative high voltage, the second negative high voltage and the third negative high voltage required by VoIP conversation are respectively generated between the three stages of Cuk converters and the ground; the circuit has the advantages of small ripple current, no pulsation of input current and outpu